wpi: Fix a lock leak in an error path in wpi_run()

PR:		258243
Reported by:	dinghao.liu@zju.edu.cn
MFC after:	1 week

sys/dev/wpi/if_wpi.c

@@ -4547,6 +4547,7 @@ wpi_run(struct wpi_softc *sc, struct ieee80211vap *vap)
 	    sc->rxon.chan, sc->rxon.flags);
 
 	if ((error = wpi_send_rxon(sc, 0, 1)) != 0) {
+		WPI_RXON_UNLOCK(sc);
 		device_printf(sc->sc_dev, "%s: could not send RXON\n",
 		    __func__);
 		return error;