WIRELESS: at76c50x, remove unneeded NULL check

Stanse found that urb cannot be NULL in at76_rx_tasklet because it is
dereferenced earlier, so remove the unneeded check.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/at76c50x-usb.c

@@ -1525,7 +1525,6 @@ static void at76_rx_tasklet(unsigned long param)
 
 	if (priv->device_unplugged) {
 		at76_dbg(DBG_DEVSTART, "device unplugged");
-		if (urb)
 		at76_dbg(DBG_DEVSTART, "urb status %d", urb->status);
 		return;
 	}