IB/uverbs: Expose RSS related capabilities

Query RSS related attributes and return them to user-space via the
extended query device uverbs command.

It includes both direct ones (i.e. struct ib_uverbs_rss_caps) and
max_wq_type_rq which may be used in both RSS and non RSS flows.

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