IB/mlx4: Don't call dma_free_coherent() with irqs disabled

mlx4_ib_free_cq_buf() should not be called under spin_lock_irq() since
it calls dma_free_coherent(), which needs irqs enabled.  Fix this by
deferring the free to outside the locked region.

This was found due to the

	WARN_ON(irqs_disabled());

in swiotlb_free_coherent().
Signed-off-by: Vladimir Sokolovsky <vlad@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/mlx4/cq.c

@@ -397,10 +397,14 @@ int mlx4_ib_resize_cq(struct ib_cq *ibcq, int entries, struct ib_udata *udata)
 		cq->resize_buf = NULL;
 		cq->resize_umem = NULL;
 	} else {
+		struct mlx4_ib_cq_buf tmp_buf;
+		int tmp_cqe = 0;
+
 		spin_lock_irq(&cq->lock);
 		if (cq->resize_buf) {
 			mlx4_ib_cq_resize_copy_cqes(cq);
-			mlx4_ib_free_cq_buf(dev, &cq->buf, cq->ibcq.cqe);
+			tmp_buf = cq->buf;
+			tmp_cqe = cq->ibcq.cqe;
 			cq->buf      = cq->resize_buf->buf;
 			cq->ibcq.cqe = cq->resize_buf->cqe;
 
@@ -408,6 +412,9 @@ int mlx4_ib_resize_cq(struct ib_cq *ibcq, int entries, struct ib_udata *udata)
 			cq->resize_buf = NULL;
 		}
 		spin_unlock_irq(&cq->lock);
+
+		if (tmp_cqe)
+			mlx4_ib_free_cq_buf(dev, &tmp_buf, tmp_cqe);
 	}
 
 	goto out;