wifi: mt76: mt7996: use correct link_id when filling TXD and TXP

wifi: mt76: mt7996: use correct link_id when filling TXD and TXP

Obtain the correct link ID and, if needed, switch to the corresponding
wcid before populating the TX descriptor and TX payload.

Rules for link id:
- For QoS data of MLD peers (excluding EAPOL), select the primary or
  secondary wcid based on whether the TID is odd or even to meet FW/HW
  requirements
- For other packets, use IEEE80211_TX_CTRL_MLO_LINK if specified
  (such as multicast and broadcast packets)

Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20251106064203.1000505-8-shayne.chen@mediatek.com
Signed-off-by: Felix Fietkau <nbd@nbd.name>