AP_GPS: remove check for GPS_SKIP_SIRF_NMEA

libraries/AP_GPS/AP_GPS.cpp

@@ -264,7 +264,6 @@ AP_GPS::detect_instance(uint8_t instance)
             hal.console->print(" SBP ");
             new_gps = new AP_GPS_SBP(*this, state[instance], _port[instance]);
         }
-#if !defined(GPS_SKIP_SIRF_NMEA)
 		// save a bit of code space on a 1280
 		else if ((_type[instance] == GPS_TYPE_AUTO || _type[instance] == GPS_TYPE_SIRF) &&
                  AP_GPS_SIRF::_detect(dstate->sirf_detect_state, data)) {
@@ -280,7 +279,6 @@ AP_GPS::detect_instance(uint8_t instance)
 				new_gps = new AP_GPS_NMEA(*this, state[instance], _port[instance]);
 			}
 		}
-#endif
 	}
 
 #if CONFIG_HAL_BOARD == HAL_BOARD_PX4