Fix M114 E / R broken by `LIN_ADVANCE` (#21579)

Marlin/src/module/stepper.cpp

       #if EITHER(LIN_ADVANCE, MIXING_EXTRUDER)
         delta_error.e += advance_dividend.e;
         if (delta_error.e >= 0) {
-          count_position.e += count_direction.e;
           #if ENABLED(LIN_ADVANCE)
             delta_error.e -= advance_divisor;
             // Don't step E here - But remember the number of steps to perform
             motor_direction(E_AXIS) ? --LA_steps : ++LA_steps;
           #else
+            count_position.e += count_direction.e;
             step_needed.e = true;
           #endif
         }
     #if ENABLED(MIXING_EXTRUDER)
       // We don't know which steppers will be stepped because LA loop follows,
       // with potentially multiple steps. Set all.
-      if (LA_steps > 0)
+      if (LA_steps > 0) {
         MIXER_STEPPER_LOOP(j) NORM_E_DIR(j);
-      else if (LA_steps < 0)
+        count_direction.e = 1;
+      }
+      else if (LA_steps < 0) {
         MIXER_STEPPER_LOOP(j) REV_E_DIR(j);
+        count_direction.e = -1;
+      }
     #else
-      if (LA_steps > 0)
+      if (LA_steps > 0) {
         NORM_E_DIR(stepper_extruder);
-      else if (LA_steps < 0)
+        count_direction.e = 1;
+      }
+      else if (LA_steps < 0) {
         REV_E_DIR(stepper_extruder);
+        count_direction.e = -1;
+      }
     #endif
 
     DIR_WAIT_AFTER();
           AWAIT_LOW_PULSE();
       #endif
 
+      count_position.e += count_direction.e;
+
       // Set the STEP pulse ON
       #if ENABLED(MIXING_EXTRUDER)
         E_STEP_WRITE(mixer.get_next_stepper(), !INVERT_E_STEP_PIN);