IB/rdmavt: restore IRQs on error path in rvt_create_ah()

We need to call spin_unlock_irqrestore() instead of vanilla
spin_unlock() on this error path.

Fixes: 119a8e70 ("IB/rdmavt: Add AH to rdmavt")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Acked-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/sw/rdmavt/ah.c

@@ -119,7 +119,7 @@ struct ib_ah *rvt_create_ah(struct ib_pd *pd,
 
 	spin_lock_irqsave(&dev->n_ahs_lock, flags);
 	if (dev->n_ahs_allocated == dev->dparms.props.max_ah) {
-		spin_unlock(&dev->n_ahs_lock);
+		spin_unlock_irqrestore(&dev->n_ahs_lock, flags);
 		kfree(ah);
 		return ERR_PTR(-ENOMEM);
 	}