mt76: mt7921: fix inappropriate WoW setup with the missing ARP informaiton

Fix the Wake-on-WoWLAN failure should rely on ARP Information is being
updated in time to the firmware.

Fixes: ffa1bf97 ("mt76: mt7921: introduce PM support")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>