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

net/bridge/br_switchdev.c

@@ -72,7 +72,8 @@ bool nbp_switchdev_allowed_egress(const struct net_bridge_port *p,
 
 /* Flags that can be offloaded to hardware */
 #define BR_PORT_FLAGS_HW_OFFLOAD (BR_LEARNING | BR_FLOOD | \
-				  BR_MCAST_FLOOD | BR_BCAST_FLOOD | BR_PORT_LOCKED)
+				  BR_MCAST_FLOOD | BR_BCAST_FLOOD | BR_PORT_LOCKED | \
+				  BR_HAIRPIN_MODE | BR_ISOLATED | BR_MULTICAST_TO_UNICAST)
 
 int br_switchdev_set_port_flag(struct net_bridge_port *p,
 			       unsigned long flags,