ieee802154-atusb: Delete an unnecessary check before the function call "kfree_skb"

The kfree_skb() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Acked-by: NStefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

drivers/net/ieee802154/atusb.c

@@ -310,8 +310,7 @@ static void atusb_free_urbs(struct atusb *atusb)
 		urb = usb_get_from_anchor(&atusb->idle_urbs);
 		if (!urb)
 			break;
-		if (urb->context)
-			kfree_skb(urb->context);
+		kfree_skb(urb->context);
 		usb_free_urb(urb);
 	}
 }