net: thunderx: Set max queue count taking XDP_TX into account

on T81 there are only 4 cores, hence setting max queue count to 4
would leave nothing for XDP_TX. This patch fixes this by doubling
max queue count in above scenarios.

Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
Signed-off-by: cjacob <cjacob@caviumnetworks.com>
Signed-off-by: Aleksey Makarov <aleksey.makarov@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>