net: bridge: offload BR_HAIRPIN_MODE, BR_ISOLATED, BR_MULTICAST_TO_UNICAST

Add BR_HAIRPIN_MODE, BR_ISOLATED and BR_MULTICAST_TO_UNICAST port flags to
BR_PORT_FLAGS_HW_OFFLOAD so that switchdev drivers which have an offloaded
data plane have a chance to reject these bridge port flags if they don't
support them yet.

It makes the code path go through the
SWITCHDEV_ATTR_ID_PORT_PRE_BRIDGE_FLAGS driver handlers, which return
-EINVAL for everything they don't recognize.

For drivers that don't catch SWITCHDEV_ATTR_ID_PORT_PRE_BRIDGE_FLAGS at
all, switchdev will return -EOPNOTSUPP for those which is then ignored, but
those are in the minority.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20220410134227.18810-1-arinc.unal@arinc9.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>