RX vector reports channel bandwidth 320-1 and 320-2 with different
values. Fix it to correctly report rx rate when using CBW320-2.

Fixes: 80f5a31d ("wifi: mt76: mt7996: add support for EHT rate report")
Signed-off-by: Peter Chiu <chui-hao.chiu@mediatek.com>
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>