RDMA/mlx4: Add missed RSS hash inner header flag

RDMA/mlx4: Add missed RSS hash inner header flag

commit 4f9ca2d8686ecfdd40ca4f0294a3d94f83f05cea upstream.

Despite being advertised to user space application, the RSS inner
header flag was filtered by checks at the beginning of QP creation
routine.

Cc: <stable@vger.kernel.org> # 4.15
Fixes: 4d02ebd9bbbd ("IB/mlx4: Fix RSS hash fields restrictions")
Fixes: 07d84f7b6adf ("IB/mlx4: Add support to RSS hash for inner headers")
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>