RDMA/ocrdma: Always resolve destination mac from GRH for UD QPs

For user applications that use UD QPs, always resolve destination MAC
from the GRH.  This is to avoid failure due to any garbage value in
the attr->dmac.

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