net: dsa: call SWITCHDEV_FDB_OFFLOADED for the orig_dev

When switchdev_handle_fdb_event_to_device() replicates a FDB event
emitted for the bridge or for a LAG port and DSA offloads that, we
should notify back to switchdev that the FDB entry on the original
device is what was offloaded, not on the DSA slave devices that the
event is replicated on.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>