net: airoha: Support multiple LAN/WAN interfaces for hw MAC address configuration

net: airoha: Support multiple LAN/WAN interfaces for hw MAC address configuration

The EN7581 and AN7583 SoCs provide registers to configure hardware LAN/WAN
MAC addresses. These registers are used during FE hw acceleration to
determine whether received traffic is destined to this host (L3 traffic)
or should be switched to another device (L2 traffic).
The SoC hardware design assumes all interfaces configured as LAN (or WAN)
share the MAC address MSBs, which are programmed into the
REG_FE_{LAN,WAN}_MAC_H register. The LSBs of 'local' mac addresses can be
expressed as a range via the REG_FE_MAC_LMIN and REG_FE_MAC_LMAX
registers. In order to properly accelerate the traffic, FE module requires
the user to configure the REG_FE_{LAN,WAN}_MAC_H register respecting this
limitation. Please note a misconfiguration in REG_FE_{LAN,WAN}_MAC_H
will still allow the user to log into the device for debugging.
Previously, only a single interface was considered when programming these
registers. Extend the logic to derive the correct minimum and maximum
values for REG_FE_MAC_LMIN/REG_FE_MAC_LMAX when two or more interfaces are
configured as LAN or WAN. Since this functionality was not available
before this series, no regression is introduced.

Tested-by: Madhur Agrawal <madhur.agrawal@airoha.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20260603-airoha-eth-multi-serdes-v9-6-5d476bc2f426@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>