Enabled switch fallthrough checking by compiler

src/main/drivers/sdcard.c

@@ -912,6 +912,7 @@ bool sdcard_poll(void)
                         break; // Timeout not reached yet so keep waiting
                     }
                     // Timeout has expired, so fall through to convert to a fatal error
+                    FALLTHROUGH;
 
                 case SDCARD_RECEIVE_ERROR:
                     sdcard_deselect();