RDMA/efa: Introduce SRD QP state machine

This precursory patch adds the SRD QP type state machine, which is
currently identical to the one of UD QP type.  A following patch is going
to change the SRD QP state machine to support RNR retry modifications.

Link: https://lore.kernel.org/r/20200731060420.17053-4-galpress@amazon.com


Reviewed-by: Firas JahJah <firasj@amazon.com>
Reviewed-by: Yossi Leybovich <sleybo@amazon.com>
Signed-off-by: Gal Pressman <galpress@amazon.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>