net: dsa: mt7530: remove .mac_port_config for MT7988 and make it optional

net: dsa: mt7530: remove .mac_port_config for MT7988 and make it optional

For the switch on the MT7988 SoC, the mac_port_config member for ID_MT7988
in mt753x_table is not needed as the interfaces of all MACs are already
handled on mt7988_mac_port_get_caps().

Therefore, remove the mac_port_config member from ID_MT7988 in
mt753x_table. Before calling priv->info->mac_port_config(), if there's no
mac_port_config member in mt753x_table, exit mt753x_mac_config()
successfully.

Remove calling priv->info->mac_port_config() from the sanity check as the
sanity check requires a pointer to a mac_port_config function to be
non-NULL. This will fail for MT7988 as mac_port_config won't be a member of
its info table.

Co-developed-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>