net: mvpp2: fix the number of queues per cpu for PPv2.2

The Marvell PPv2.2 engine only has 8 Rx queues per CPU, while PPv2.1 has
16 of them. This patch updates the code so that the Rx queues mask width
is selected given the version of the network controller used.

Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>