nvme-rdma: fix error code in nvme_rdma_create_ctrl()

We accidentally return ERR_PTR(0) which is NULL.  The caller isn't
explicitly checking for that but I couldn't immediately spot whether
this would lead to a NULL dereference.  Anyway, we can fix add an
error code easily enough.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

drivers/nvme/host/rdma.c

@@ -1919,12 +1919,14 @@ static struct nvme_ctrl *nvme_rdma_create_ctrl(struct device *dev,
 	/* sanity check icdoff */
 	if (ctrl->ctrl.icdoff) {
 		dev_err(ctrl->ctrl.device, "icdoff is not supported!\n");
+		ret = -EINVAL;
 		goto out_remove_admin_queue;
 	}
 
 	/* sanity check keyed sgls */
 	if (!(ctrl->ctrl.sgls & (1 << 20))) {
 		dev_err(ctrl->ctrl.device, "Mandatory keyed sgls are not support\n");
+		ret = -EINVAL;
 		goto out_remove_admin_queue;
 	}