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/helix/local_drivers/i2c.h

@@ -1,5 +1,4 @@
-#ifndef I2C_H
-#define I2C_H
+#pragma once
 
 #include <stdint.h>
 
@@ -45,5 +44,3 @@ extern unsigned char i2c_readNak(void);
 extern unsigned char i2c_read(unsigned char ack);
 
 #define i2c_read(ack)  (ack) ? i2c_readAck() : i2c_readNak();
-
-#endif