RDMA/ocrdma: Avoid posting DPP requests for RDMA READ

Rollback the patch which allows DPP posting of RDMA READ since this
path is not yet stable in FW.

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>