RDMA/bnxt_re: checking for NULL instead of IS_ERR()

bnxt_re_alloc_mw() doesn't return NULL, it returns error pointers.

Fixes: 9152e0b7 ("RDMA/bnxt_re: HW workarounds for handling specific conditions")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/bnxt_re/ib_verbs.c

@@ -588,10 +588,10 @@ static int bnxt_re_create_fence_mr(struct bnxt_re_pd *pd)
 
 	/* Create a fence MW only for kernel consumers */
 	mw = bnxt_re_alloc_mw(&pd->ib_pd, IB_MW_TYPE_1, NULL);
-	if (!mw) {
+	if (IS_ERR(mw)) {
 		dev_err(rdev_to_dev(rdev),
 			"Failed to create fence-MW for PD: %p\n", pd);
-		rc = -EINVAL;
+		rc = PTR_ERR(mw);
 		goto fail;
 	}
 	fence->mw = mw;