Change keyboard level include guards to pragma once (#14248)

* Change keyboard level include guards to `pragma once`

And clean up a lot of layout macros

* Oops

* Remove dangling endif

keyboards/mitosis/config.h

@@ -15,8 +15,7 @@ You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#ifndef CONFIG_H
-#define CONFIG_H
+#pragma once
 
 #include "config_common.h"
 
@@ -66,5 +65,3 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
     UCSR1B = _BV(TXEN1) | _BV(RXEN1); \
     /* 8-bit data */                  \
     UCSR1C = _BV(UCSZ11) | _BV(UCSZ10);
-
-#endif