staging: fsl-dpaa2: ethsw: Handle PORT_PRE_BRIDGE_FLAGS

In preparation for removing SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS_SUPPORT,
handle the SWITCHDEV_ATTR_ID_PORT_PRE_BRIDGE_FLAGS attribute and check
that the bridge port flags being configured are supported.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>