Turn off laser power pin when PWM goes to 0

Marlin/Marlin_main.cpp

@@ -6449,6 +6449,7 @@ inline void gcode_G92() {
         const float spindle_laser_power = parser.floatval('S');
         if (spindle_laser_power == 0) {
           WRITE(SPINDLE_LASER_ENABLE_PIN, !SPINDLE_LASER_ENABLE_INVERT);                                    // turn spindle off (active low)
+          analogWrite(SPINDLE_LASER_PWM_PIN, SPINDLE_LASER_PWM_INVERT ? 255 : 0);                           // only write low byte
           delay_for_power_down();
         }
         else {