wifi: mt76: mt7921: fix the unfinished command of regd_notifier before suspend

Before entering suspend, we need to ensure that all MCU command are
completed. In some cases, such as with regd_notifier, there is a
chance that CLC commands, will be executed before suspend.

Signed-off-by: Ming Yen Hsieh <mingyen.hsieh@mediatek.com>
Signed-off-by: Leon Yen <leon.yen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>