net: ethernet: mtk_eth_soc: fix hw hash reporting for MTK_NETSYS_V2

Properly report hw rx hash for mt7986 chipset accroding to the new dma
descriptor layout.

Fixes: 197c9e9b

 ("net: ethernet: mtk_eth_soc: introduce support for mt7986 chipset")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/091394ea4e705fbb35f828011d98d0ba33808f69.1661257293.git.lorenzo@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>