staging: rtl8192e: Unlock mutex for one line in rtllib_stop_protocol()

The following command uses the mutex ieee->wx_mutex:
cancel_delayed_work_sync(&ieee->associate_retry_wq)
Therefore it cannot be canceled with ieee->wx_mutex locked.
rtllib_stop_protocol() is always called with ieee->wx_mutex locked so
according line can be unlocked.
Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/ffe60e8f6e29197f331e239ab38154da97c743be.1695582999.git.philipp.g.hortmann@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8192e/rtllib_softmac.c

@@ -2307,7 +2307,9 @@ void rtllib_stop_protocol(struct rtllib_device *ieee, u8 shutdown)
 	}
 
 	del_timer_sync(&ieee->associate_timer);
+	mutex_unlock(&ieee->wx_mutex);
 	cancel_delayed_work_sync(&ieee->associate_retry_wq);
+	mutex_lock(&ieee->wx_mutex);
 	cancel_delayed_work_sync(&ieee->link_change_wq);
 	rtllib_stop_scan(ieee);