wifi: mt76: mt7996: Fix secondary link lookup in mt7996_mcu_sta_mld_setup_tlv()

Use proper link_id value for secondary link lookup in
mt7996_mcu_sta_mld_setup_tlv routine.

Fixes: 00cef41d ("wifi: mt76: mt7996: Add mt7996_mcu_sta_mld_setup_tlv() and mt7996_mcu_sta_eht_mld_tlv()")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20250704-mt7996-mlo-fixes-v1-2-356456c73f43@kernel.org


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