wifi: mt76: mt7925: fix wrong band_idx setting when enable sniffer mode

Currently, sniffer mode does not support band auto,
so set band_idx to the default 0.

Fixes: 0cb349d7 ("wifi: mt76: mt7925: update mt7925_mac_link_bss_add for MLO")
Signed-off-by: Eric-SY Chang <eric-sy.chang@mediatek.com>
Signed-off-by: Ming Yen Hsieh <mingyen.hsieh@mediatek.com>
Link: https://patch.msgid.link/20241101074340.26176-1-mingyen.hsieh@mediatek.com


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