Apply #pragma once, misc cleanup (#12322)

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

Marlin/src/module/endstops.h

@@ -19,14 +19,12 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  *
  */
+#pragma once
 
 /**
  * endstops.h - manages endstops
  */
 
-#ifndef __ENDSTOPS_H__
-#define __ENDSTOPS_H__
-
 #include "../inc/MarlinConfig.h"
 #include <stdint.h>
 
@@ -173,5 +171,3 @@ class Endstops {
 };
 
 extern Endstops endstops;
-
-#endif // __ENDSTOPS_H__