Support create/modify/destroy WQ related verbs.

The base IB object to enable RSS functionality is a WQ (i.e. ib_wq).
This patch implements the related WQ verbs as of create, modify and
destroy.

In downstream patches the WQ will be used as part of an indirection
table (i.e. ib_rwq_ind_table) to enable RSS QP creation.

Notes:
ConnectX-3 hardware requires consecutive WQNs list as receive descriptor
queues for the RSS QP. Hence, the driver manages consecutive ranges lists
per context which the user must respect.
Destroying the WQ does not return its WQN back to its range for
reusing. However, destroying all WQs from the same range releases the
range and in turn releases its WQNs for reusing.

Since the WQ object is not a natural object in the hardware, the driver
implements the WQ by the hardware QP.

As such, the WQ inherits its port from its RSS QP parent upon its
RST->INIT transition and by that time its state is applied to the
hardware.
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>