net: atlantic: always use random TC-queue mapping for TX on A2.

This patch changes the TC-queue mapping mechanism used on A2.
Configure the A2 HW in such a way that we can keep queue index mapping
exactly as it was on A1.

Signed-off-by: Mark Starovoytov <mstarovoitov@marvell.com>
Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>