net: dsa: microchip: add IPV information support

Most of Microchip KSZ switches use Internal Priority Value associated
with every frame. For example, it is possible to map any VLAN PCP or
DSCP value to IPV and at the end, map IPV to a queue.

Since amount of IPVs is not equal to amount of queues, add this
information and make use of it in some functions.

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>