wifi: mt76: mt7925: add mt7925_mac_link_bss_add to create per-link BSS

The mt7925_mac_link_bss_add function currently creates the per-link BSS.
We will extend this function when we implement the MLO functionality.

This patch only includes structural changes and does not involve any
logic changes.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Link: https://patch.msgid.link/20240613030241.5771-46-sean.wang@kernel.org


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