net: mvpp2: initialize the RSS tables

This patch initialize the RSS tables to evenly (depending on the packets
RSS hashes) distribute the packets across port Rx queues. This helps to
handle packets on different CPUs to improve performances, as more queues
will be used in parallel.

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