IB/mlx4: Check that reserved fields in mlx4_ib_create_qp_rss are zero

According to mlx4 convention, need to fail the command due to a non-zero
value in the user data which is expected to be zero.

Fixes: 3078f5f1 ("IB/mlx4: Add support for RSS QP")
Signed-off-by: Guy Levi <guyle@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>