Apply #pragma once, misc cleanup (#12322)

* Apply #pragma once in headers
* Adjust some thermistors formatting
* Misc cleanup and formatting

Marlin/src/HAL/platforms.h

@@ -1,7 +1,25 @@
-#ifndef _HAL_PLATFORMS_H_
-#define _HAL_PLATFORMS_H_
-
-#ifndef HAL_PLATFORM
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * 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
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#pragma once
 
 #ifdef __AVR__
   #define HAL_PLATFORM HAL_AVR
@@ -27,10 +45,6 @@
   #error "Unsupported Platform!"
 #endif
 
-#endif // HAL_PLATFORM
-
 #define XSTR_(M) #M
 #define XSTR(M) XSTR_(M)
 #define HAL_PATH(PATH, NAME) XSTR(PATH/HAL_PLATFORM/NAME)
-
-#endif // _HAL_PLATFORMS_H_