AP_HAL_PX4: UARTDriver: fix trailing whitespaces

libraries/AP_HAL_PX4/UARTDriver.cpp

@@ -383,6 +383,7 @@ int PX4UARTDriver::_write_fd(const uint8_t *buf, uint16_t n)
 #else
         _last_write_time = AP_HAL::micros64();
 #endif
+
         // we haven't done a successful write for 2ms, which means the
         // port is running at less than 500 bytes/sec. Start
         // discarding bytes, even if this is a blocking port. This
@@ -480,5 +481,4 @@ void PX4UARTDriver::_timer_tick(void)
     _in_timer = false;
 }
 
-#endif // CONFIG_HAL_BOARD
-
+#endif