wifi: mt76: mt7915: remove BW160 and BW80+80 support

Remove BW160 and BW80+80 capability in mt7915.

Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Ryder Lee <ryder.lee@mediatek.com>
Reviewed-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Money <Wang&lt;Money.Wang@mediatek.com>
Signed-off-by: MeiChia Chiu <MeiChia.Chiu@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>