RDMA/ocrdma: Get vlan tag from ib_qp_attrs

After IP-based GID changes, VLAN id can be obtained from
qp_attr->vlan_id.

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>