wifi: mt76: mt7996: use the correct vif link for scanning/roc

restore fix which was dropped during MLO rework

Fixes: f0b0b239 ("wifi: mt76: mt7996: rework mt7996_mac_write_txwi() for MLO support")
Signed-off-by: Chad Monroe <chad@monroe.io>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/180fffd409aa57f535a3d2c1951e41ae398ce09e.1754659732.git.chad@monroe.io


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