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

quantum/serial_link/protocol/byte_stuffer.h

@@ -22,8 +22,7 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 */
 
-#ifndef SERIAL_LINK_BYTE_STUFFER_H
-#define SERIAL_LINK_BYTE_STUFFER_H
+#pragma once
 
 #include <stdint.h>
 
@@ -33,5 +32,3 @@ SOFTWARE.
 void init_byte_stuffer(void);
 void byte_stuffer_recv_byte(uint8_t link, uint8_t data);
 void byte_stuffer_send_frame(uint8_t link, uint8_t* data, uint16_t size);
-
-#endif