RDMA/mlx4: Return missed an error if device doesn't support steering

[ Upstream commit f4e56ec4452f48b8292dcf0e1c4bdac83506fb8b ]

The error flow fixed in this patch is not possible because all kernel
users of create QP interface check that device supports steering before
set IB_QP_CREATE_NETIF_QP flag.

Fixes: c1c98501 ("IB/mlx4: Add support for steerable IB UD QPs")
Link: https://lore.kernel.org/r/91c61f6e60eb0240f8bbc321fda7a1d2986dd03c.1634023677.git.leonro@nvidia.com


Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>