xen/pvcalls: remove redundant check for irq >= 0

This is a moot point, but irq is always less than zero at the label
out_error, so the check for irq >= 0 is redundant and can be removed.

Detected by CoverityScan, CID#1460371 ("Logically dead code")

Fixes: cb1c7d9bbc87 ("xen/pvcalls: implement connect command")
Signed-off-by: Colin Ian King <[e-mail]>
Reviewed-by: Juergen Gross <[e-mail]>
Signed-off-by: Boris Ostrovsky <[e-mail]>

drivers/xen/pvcalls-front.c

···
 	return 0;
 
 out_error:
-	if (irq >= 0)
-		unbind_from_irqhandler(irq, map);
-	else if (*evtchn >= 0)
+	if (*evtchn >= 0)
 		xenbus_free_evtchn(pvcalls_front_dev, *evtchn);
 	kfree(map->active.data.in);
 	kfree(map->active.ring);