net: airoha: Fix smac_id configuration in bridge mode

Set PPE entry smac_id field to 0xf in airoha_ppe_foe_commit_subflow_entry
routine for IPv6 traffic in order to instruct the hw to keep original
source mac address for IPv6 hw accelerated traffic in bridge mode.

Fixes: cd53f622 ("net: airoha: Add L2 hw acceleration support")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250602-airoha-flowtable-ipv6-fix-v2-3-3287f8b55214@kernel.org


Signed-off-by: Paolo Abeni <pabeni@redhat.com>