Add AXIS_HAS_SQUARE_WAVE shorthand

Marlin/src/module/stepper_indirection.h

 void restore_stepper_drivers();  // Called by PSU_ON
 void reset_stepper_drivers();    // Called by settings.load / settings.reset
 
+#define AXIS_HAS_SQUARE_WAVE(A) (AXIS_IS_TMC(A) && ENABLED(SQUARE_WAVE_STEPPING))
+
 // X Stepper
 #if AXIS_DRIVER_TYPE_X(L6470)
   extern L6470 stepperX;
   #define X_DIR_READ READ(X_DIR_PIN)
 #endif
 #define X_STEP_INIT SET_OUTPUT(X_STEP_PIN)
-#if AXIS_IS_TMC(X) && ENABLED(SQUARE_WAVE_STEPPING)
+#if AXIS_HAS_SQUARE_WAVE(X)
   #define X_STEP_WRITE(STATE) do { if(STATE) TOGGLE(X_STEP_PIN); } while(0)
 #else
   #define X_STEP_WRITE(STATE) WRITE(X_STEP_PIN,STATE)
   #define Y_DIR_READ READ(Y_DIR_PIN)
 #endif
 #define Y_STEP_INIT SET_OUTPUT(Y_STEP_PIN)
-#if AXIS_IS_TMC(Y) && ENABLED(SQUARE_WAVE_STEPPING)
+#if AXIS_HAS_SQUARE_WAVE(Y)
   #define Y_STEP_WRITE(STATE) do { if (STATE) TOGGLE(Y_STEP_PIN); } while(0)
 #else
   #define Y_STEP_WRITE(STATE) WRITE(Y_STEP_PIN,STATE)
   #define Z_DIR_READ READ(Z_DIR_PIN)
 #endif
 #define Z_STEP_INIT SET_OUTPUT(Z_STEP_PIN)
-#if AXIS_IS_TMC(Z) && ENABLED(SQUARE_WAVE_STEPPING)
+#if AXIS_HAS_SQUARE_WAVE(Z)
   #define Z_STEP_WRITE(STATE) do { if(STATE) TOGGLE(Z_STEP_PIN); } while(0)
 #else
   #define Z_STEP_WRITE(STATE) WRITE(Z_STEP_PIN,STATE)
     #define X2_DIR_READ READ(X2_DIR_PIN)
   #endif
   #define X2_STEP_INIT SET_OUTPUT(X2_STEP_PIN)
-  #if AXIS_IS_TMC(X2) && ENABLED(SQUARE_WAVE_STEPPING)
+  #if AXIS_HAS_SQUARE_WAVE(X2)
     #define X2_STEP_WRITE(STATE) do { if(STATE) TOGGLE(X2_STEP_PIN); } while(0)
   #else
     #define X2_STEP_WRITE(STATE) WRITE(X2_STEP_PIN,STATE)
     #define Y2_DIR_READ READ(Y2_DIR_PIN)
   #endif
   #define Y2_STEP_INIT SET_OUTPUT(Y2_STEP_PIN)
-  #if AXIS_IS_TMC(Y2) && ENABLED(SQUARE_WAVE_STEPPING)
+  #if AXIS_HAS_SQUARE_WAVE(Y2)
     #define Y2_STEP_WRITE(STATE) do { if(STATE) TOGGLE(Y2_STEP_PIN); } while(0)
   #else
     #define Y2_STEP_WRITE(STATE) WRITE(Y2_STEP_PIN,STATE)
     #define Z2_DIR_READ READ(Z2_DIR_PIN)
   #endif
   #define Z2_STEP_INIT SET_OUTPUT(Z2_STEP_PIN)
-  #if AXIS_IS_TMC(Z2) && ENABLED(SQUARE_WAVE_STEPPING)
+  #if AXIS_HAS_SQUARE_WAVE(Z2)
     #define Z2_STEP_WRITE(STATE) do { if(STATE) TOGGLE(Z2_STEP_PIN); } while(0)
   #else
     #define Z2_STEP_WRITE(STATE) WRITE(Z2_STEP_PIN,STATE)
     #define Z3_DIR_READ READ(Z3_DIR_PIN)
   #endif
   #define Z3_STEP_INIT SET_OUTPUT(Z3_STEP_PIN)
-  #if AXIS_IS_TMC(Z3) && ENABLED(SQUARE_WAVE_STEPPING)
+  #if AXIS_HAS_SQUARE_WAVE(Z3)
     #define Z3_STEP_WRITE(STATE) do { if(STATE) TOGGLE(Z3_STEP_PIN); } while(0)
   #else
     #define Z3_STEP_WRITE(STATE) WRITE(Z3_STEP_PIN,STATE)
   #define E0_DIR_READ READ(E0_DIR_PIN)
 #endif
 #define E0_STEP_INIT SET_OUTPUT(E0_STEP_PIN)
-#if AXIS_IS_TMC(E0) && ENABLED(SQUARE_WAVE_STEPPING)
+#if AXIS_HAS_SQUARE_WAVE(E0)
   #define E0_STEP_WRITE(STATE) do { if(STATE) TOGGLE(E0_STEP_PIN); } while(0)
 #else
   #define E0_STEP_WRITE(STATE) WRITE(E0_STEP_PIN,STATE)
   #define E1_DIR_READ READ(E1_DIR_PIN)
 #endif
 #define E1_STEP_INIT SET_OUTPUT(E1_STEP_PIN)
-#if AXIS_IS_TMC(E1) && ENABLED(SQUARE_WAVE_STEPPING)
+#if AXIS_HAS_SQUARE_WAVE(E1)
   #define E1_STEP_WRITE(STATE) do { if(STATE) TOGGLE(E1_STEP_PIN); } while(0)
 #else
   #define E1_STEP_WRITE(STATE) WRITE(E1_STEP_PIN,STATE)
   #define E2_DIR_READ READ(E2_DIR_PIN)
 #endif
 #define E2_STEP_INIT SET_OUTPUT(E2_STEP_PIN)
-#if AXIS_IS_TMC(E2) && ENABLED(SQUARE_WAVE_STEPPING)
+#if AXIS_HAS_SQUARE_WAVE(E2)
   #define E2_STEP_WRITE(STATE) do { if(STATE) TOGGLE(E2_STEP_PIN); } while(0)
 #else
   #define E2_STEP_WRITE(STATE) WRITE(E2_STEP_PIN,STATE)
   #define E3_DIR_READ READ(E3_DIR_PIN)
 #endif
 #define E3_STEP_INIT SET_OUTPUT(E3_STEP_PIN)
-#if AXIS_IS_TMC(E3) && ENABLED(SQUARE_WAVE_STEPPING)
+#if AXIS_HAS_SQUARE_WAVE(E3)
   #define E3_STEP_WRITE(STATE) do { if(STATE) TOGGLE(E3_STEP_PIN); } while(0)
 #else
   #define E3_STEP_WRITE(STATE) WRITE(E3_STEP_PIN,STATE)
   #define E4_DIR_READ READ(E4_DIR_PIN)
 #endif
 #define E4_STEP_INIT SET_OUTPUT(E4_STEP_PIN)
-#if AXIS_IS_TMC(E4) && ENABLED(SQUARE_WAVE_STEPPING)
+#if AXIS_HAS_SQUARE_WAVE(E4)
   #define E4_STEP_WRITE(STATE) do { if(STATE) TOGGLE(E4_STEP_PIN); } while(0)
 #else
   #define E4_STEP_WRITE(STATE) WRITE(E4_STEP_PIN,STATE)
   #define E5_DIR_READ READ(E5_DIR_PIN)
 #endif
 #define E5_STEP_INIT SET_OUTPUT(E5_STEP_PIN)
-#if AXIS_IS_TMC(E5) && ENABLED(SQUARE_WAVE_STEPPING)
+#if AXIS_HAS_SQUARE_WAVE(E5)
   #define E5_STEP_WRITE(STATE) do { if(STATE) TOGGLE(E5_STEP_PIN); } while(0)
 #else
   #define E5_STEP_WRITE(STATE) WRITE(E5_STEP_PIN,STATE)