net: thunderx: Configure RED and backpressure levels

This patch enables moving average calculation of Rx pkt's resources
and configures RED and backpressure levels for both CQ and RBDR.
Also initialize SQ's CQ_LIMIT properly.

Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>