wifi: mt76: connac: fix checksum offload fields of connac3 RXD

Fix incorrect RXD offset and bitfield related to RX checksum offload.

Fixes: 98686cd2 ("wifi: mt76: mt7996: add driver for MediaTek Wi-Fi 7 (802.11be) devices")
Fixes: 4e9011fc ("wifi: mt76: connac: move connac3 definitions in mt76_connac3_mac.h")
Co-developed-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Peter Chiu <chui-hao.chiu@mediatek.com>
Link: https://patch.msgid.link/20240816095040.2574-1-shayne.chen@mediatek.com


Signed-off-by: Felix Fietkau <nbd@nbd.name>