net: dsa: microchip: dcb: add special handling for KSZ88X3 family

net: dsa: microchip: dcb: add special handling for KSZ88X3 family

KSZ88X3 switches have different behavior on different ports:
- It seems to be not possible to disable VLAN PCP classification on port
  2. It means, as soon as mutliqueue support is enabled, frames with
     VLAN tag will get PCP prios. This behavior do not affect Port 1 -
     it is possible to disable PCP prios.
- DSCP classification is not working on Port 2.

Since there are still usable configuration combinations, I added some
quirks to make sure user will get appropriate error message if not
possible configuration is chosen.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>