IB/mlx4: Add report for RSS capabilities by vendor channel

The mlx4's RSS patches submission missed a report of RSS capabilities
which should be reported by the vendor channel in query_device.

Signed-off-by: Guy Levi <guyle@mellanox.com>
Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>