octeontx2-af: DMAC filter support in MAC block

MAC block supports 32 dmac filters which are logically
divided among all attached LMACS.

For example MAC block0 having one LMAC then maximum supported
filters are 32 where as MAC block1 having 4 enabled LMACS
them maximum supported filteres are 8 for each LMAC.

This patch adds mbox handlers to add/delete/update mac entry
in DMAC filter table.

Signed-off-by: Sunil Kumar Kori <skori@marvell.com>
Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Signed-off-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>