wifi: mt76: mt7996: set vif default link_id adding/removing vif links

This info will be consumed by subsequent patches (e.g. in set/get tsf
routines).

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20250312-b4-mt7996-mlo-p2-v1-18-015b3d6fd928@kernel.org


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