octeontx2-af: Support for setting MAC address

Added a new mailbox message for a PF/VF to set/update
it's NIXLF's MAC address. Also updates unicast NPC
MCAM entry with this address as matching DMAC.

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