HAL whitespace and style cleanup

Marlin/src/HAL/HAL_DUE/HAL_Due.cpp

@@ -1,9 +1,9 @@
 /* **************************************************************************
- 
+
  Marlin 3D Printer Firmware
  Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
  Copyright (c) 2016 Bob Cousins bobcousins42@googlemail.com
-   
+
  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
@@ -93,7 +93,7 @@ uint8_t HAL_get_reset_source (void) {
   }
 }
 
-void _delay_ms(int delay_ms) {
+void _delay_ms(const int delay_ms) {
   // todo: port for Due?
   delay(delay_ms);
 }