IB/rxe: add RXE_START_MASK for rxe_opcode IB_OPCODE_RC_SEND_ONLY_INV

w/o RXE_START_MASK, the last_psn of IB_OPCODE_RC_SEND_ONLY_INV
will not be updated in update_wqe_psn, and the corresponding
wqe will not be acked in rxe_completer due to its last_psn is
zero. Finally, the other wqe will also not be able to be acked,
because the wqe of IB_OPCODE_RC_SEND_ONLY_INV with last_psn 0
is still there. This causes large amount of io timeout when
nvmeof is over rxe.

Add RXE_START_MASK for IB_OPCODE_RC_SEND_ONLY_INV to fix this.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Reviewed-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>