wifi: mt76: mt7925: publish msta->link after successful link add

wifi: mt76: mt7925: publish msta->link after successful link add

Move the msta->link[link_id] publication until after
mt7925_mac_link_sta_add() succeeds.

msta->link[] is RCU-visible, so publishing it before setup completes can
expose a link whose add path later fails. Publish it only after success
to avoid partially initialized link state becoming visible.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Link: https://patch.msgid.link/20260306232238.2039675-19-sean.wang@kernel.org
Signed-off-by: Felix Fietkau <nbd@nbd.name>