HW beacon filter command is being applied until we're in associated state
because the command would rely on the associated access point's beacon
interval and DTIM information.

Fixes: 7124198a ("mt76: mt7615: enable beacon filtering by default for offload fw")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>