wl1251: use ieee80211_rx_ni()

Because of SPI and SDIO wl1251 does everything in a workqueue, including
calling ieee80211_rx() which should be called with bottom halves disabled.
An error message is emitted because of this:

NOHZ: local_softirq_pending 08

Fix this by using ieee80211_rx_ni().
Signed-off-by: NKalle Valo <kalle.valo@nokia.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/wl12xx/wl1251_rx.c

@@ -153,7 +153,7 @@ static void wl1251_rx_body(struct wl1251 *wl,
 		     beacon ? "beacon" : "");
 
 	memcpy(IEEE80211_SKB_RXCB(skb), &status, sizeof(status));
-	ieee80211_rx(wl->hw, skb);
+	ieee80211_rx_ni(wl->hw, skb);
 }
 
 static void wl1251_rx_ack(struct wl1251 *wl)