net: ethernet: mtk_eth_soc: enable rx cksum offload for MTK_NETSYS_V2

Enable rx checksum offload for mt7986 chipset.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/c8699805c18f7fd38315fcb8da2787676d83a32c.1654544585.git.lorenzo@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>