RDMA/ocrdma: Use VID 0 if PFC is enabled and vlan is not configured

If the adapter ports are in PFC mode and VLAN is not configured,
use vlan tag 0 for RoCE traffic. Also, log an advisory message
in system logs.

Signed-off-by: Padmanabh Ratnakar <padmanabh.ratnakar@avagotech.com>
Signed-off-by: Devesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: Selvin Xavier <selvin.xavier@avagotech.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>