IB/uverbs: Extend create QP to get RWQ indirection table

User applications that want to spread incoming traffic between several WQs
should create a QP which contains an indirection table.

When such a QP is created other receive side parameters are not valid
and should not be given. Its send side is optional and assumed active
based on max_send_wr capability value.

Extend create QP to work accordingly.

Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Matan Barak <matanb@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Doug Ledford <dledford@redhat.com>