RDMA/ocrdma: Allow only SEND opcode in case of UD QPs

Prevent posting opcodes other than send and send immediate on the UD QPs.

Signed-off-by: Mitesh Ahuja <mitesh.ahuja@emulex.Com>
Signed-off-by: Devesh Sharma <devesh.sharma@emulex.com>
Signed-off-by: Selvin Xavier <selvin.xavier@emulex.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>