Change include guards in tmk_core/ and drivers/ to pragma once (#11240)

drivers/avr/i2c_master.h

@@ -17,8 +17,7 @@
  * GitHub repository: https://github.com/g4lvanix/I2C-master-lib
  */
 
-#ifndef I2C_MASTER_H
-#define I2C_MASTER_H
+#pragma once
 
 #define I2C_READ 0x01
 #define I2C_WRITE 0x00
@@ -42,5 +41,3 @@ i2c_status_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16
 i2c_status_t i2c_writeReg(uint8_t devaddr, uint8_t regaddr, const uint8_t* data, uint16_t length, uint16_t timeout);
 i2c_status_t i2c_readReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);
 void         i2c_stop(void);
-
-#endif  // I2C_MASTER_H