Fix init of power supply pin

Fix #13184

Marlin/src/Marlin.cpp

   #endif
   #if HAS_POWER_SWITCH
     #if ENABLED(PS_DEFAULT_OFF)
-      PSU_OFF();
+      powersupply_on = true;  PSU_OFF();
     #else
-      PSU_ON();
+      powersupply_on = false; PSU_ON();
     #endif
   #endif
 }
  * Stepper Reset (RigidBoard, et.al.)
  */
 #if HAS_STEPPER_RESET
-  void disableStepperDrivers() {
-    OUT_WRITE(STEPPER_RESET_PIN, LOW);  // drive it down to hold in reset motor driver chips
-  }
-  void enableStepperDrivers() { SET_INPUT(STEPPER_RESET_PIN); }  // set to input, which allows it to be pulled high by pullups
+  void disableStepperDrivers() { OUT_WRITE(STEPPER_RESET_PIN, LOW); } // Drive down to keep motor driver chips in reset
+  void enableStepperDrivers()  { SET_INPUT(STEPPER_RESET_PIN); }      // Set to input, allowing pullups to pull the pin high
 #endif
 
 #if ENABLED(EXPERIMENTAL_I2CBUS) && I2C_SLAVE_ADDRESS > 0

Marlin/src/gcode/control/M80_M81.cpp

   #endif
 
   // Could be moved to a feature, but this is all the data
-  bool powersupply_on = (
-    #if ENABLED(PS_DEFAULT_OFF)
-      false
-    #else
-      true
-    #endif
-  );
+  bool powersupply_on;
 
   #if HAS_TRINAMIC
     #include "../../feature/tmc_util.h"