net: ethernet: mtk_ppe: add MTK_FOE_ENTRY_V{1,2}_SIZE macros

Introduce MTK_FOE_ENTRY_V{1,2}_SIZE macros in order to make more
explicit foe_entry size for different chipset revisions.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>