octeontx2-af: Reset NIXLF's Rx/Tx stats

This patch adds a new mailbox message to reset
a NIXLF's receive and transmit HW stats.

Signed-off-by: Vamsi Attunuru <vamsi.attunuru@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>