IB/cma: Honor traffic class from lower netdevice for RoCE

When a macvlan netdevice is used for RoCE, consider the tos->prio->tc
mapping as SL using its lower netdevice.

1. If the lower netdevice is a VLAN netdevice, consider the VLAN netdevice
   and it's parent netdevice for mapping
2. If the lower netdevice is not a VLAN netdevice, consider tc mapping
   directly from the lower netdevice

Link: https://lore.kernel.org/r/20191015072058.17347-1-leon@kernel.org


Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>