1) In post recv, don't ring the DB doorbell if the QP is in RTR state.
   Cache the DB calls, until the QP is moved to RTS state.
2) Add max_rd_sge support to dev->attr.
3) Code cleanup in alloc_pd path.
Signed-off-by: NNaresh Gottumukkala <bgottumukkala@emulex.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>