Change include guards in quantum/ to pragma once (#11239)

quantum/keycode_config.h

@@ -14,13 +14,12 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #include "eeconfig.h"
 #include "keycode.h"
 #include "action_code.h"
 
-#ifndef KEYCODE_CONFIG_H
-#    define KEYCODE_CONFIG_H
-
 uint16_t keycode_config(uint16_t keycode);
 uint8_t  mod_config(uint8_t mod);
 
@@ -42,5 +41,3 @@ typedef union {
 } keymap_config_t;
 
 extern keymap_config_t keymap_config;
-
-#endif /* KEYCODE_CONFIG_H */