staging: gdm724x: use GFP_ATOMIC under spin lock

A spin lock is taken here so we should use GFP_ATOMIC.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gdm724x/gdm_mux.c

@@ -409,7 +409,7 @@ static int gdm_mux_send(void *priv_dev, void *data, int len, int tty_index,
 			  gdm_mux_send_complete,
 			  t);
 
-	ret = usb_submit_urb(t->urb, GFP_KERNEL);
+	ret = usb_submit_urb(t->urb, GFP_ATOMIC);
 
 	spin_unlock_irqrestore(&mux_dev->write_lock, flags);