Fix possible mutex double-locking

From: Milan Plzik <milan.plzik@gmail.com>

After finishing scan, at76_dwork_hw_scan locks priv->mtx and calls
ieee80211_scan_completed, which in turn can possibly call at76_config,
which tries to lock the mutex again.
---

 drivers/net/wireless/at76_usb.c |    8 ++------
 1 files changed, 2 insertions(+), 6 deletions(-)


diff --git a/drivers/net/wireless/at76_usb.c b/drivers/net/wireless/at76_usb.c
index 33fa026..e1769c0 100644
--- a/drivers/net/wireless/at76_usb.c
+++ b/drivers/net/wireless/at76_usb.c
@@ -1900,8 +1900,6 @@ static void at76_dwork_hw_scan(struct work_struct *work)
 					      dwork_hw_scan.work);
 	int ret;
 
-	mutex_lock(&priv->mtx);
-
 	ret = at76_get_cmd_status(priv->udev, CMD_SCAN);
 	at76_dbg(DBG_MAC80211, "%s: CMD_SCAN status 0x%02x", __func__, ret);
 
@@ -1912,16 +1910,14 @@ static void at76_dwork_hw_scan(struct work_struct *work)
 				   SCAN_POLL_INTERVAL);
 		goto exit;
 	}
-
+	
 	ieee80211_scan_completed(priv->hw);
 
 	if (is_valid_ether_addr(priv->bssid))
 		at76_join(priv);
 
-	ieee80211_start_queues(priv->hw);
-
 exit:
-	mutex_unlock(&priv->mtx);
+	return;
 }
 
 static int at76_hw_scan(struct ieee80211_hw *hw, u8 *ssid, size_t len)
