net/mlx4: fix indirection table error rollback

net/mlx4: fix indirection table error rollback

In case of error occurring while setting up indirection table and
related RSS context resources, intermediate objects are not cleaned up.

Moreover although unlikely, an error other than EINVAL (e.g. ENOMEM)
may be returned.

A description of mlx4_rss_attach()'s return value is also missing.

Fixes: 078b8b452e6b ("net/mlx4: add RSS flow rule action support")

Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
Acked-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>