RDMA/qedr: Initialize byte_len in WC of READ and SEND commands

Initialize byte_len in work completion of RDMA_READ and RDMA_SEND.
Exposed by uDAPL application.

Signed-off-by: Michal Kalderon <Michal.Kalderon@cavium.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>