net: dsa: mt7530: Fix traffic flooding for MMIO devices

[ Upstream commit ccc2f5a4 ]

On MMIO devices (e.g. MT7988 or EN7581) unicast traffic received on lanX
port is flooded on all other user ports if the DSA switch is configured
without VLAN support since PORT_MATRIX in PCR regs contains all user
ports. Similar to MDIO devices (e.g. MT7530 and MT7531) fix the issue
defining default VLAN-ID 0 for MT7530 MMIO devices.

Fixes: 110c18bf ("net: dsa: mt7530: introduce driver for MT7988 built-in switch")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Chester A. Unal <chester.a.unal@arinc9.com>
Link: https://patch.msgid.link/20250304-mt7988-flooding-fix-v1-1-905523ae83e9@kernel.org


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