wifi: mt76: mt7996: fix teardown command for an MLD peer

wifi: mt76: mt7996: fix teardown command for an MLD peer

[ Upstream commit e077071e7ac48d5453072f615d51629891c5b90d ]

For an MLD peer, we only need to call the teardown command when removing
the last link, and there's no need to call mt7996_mcu_add_sta() for the
earlier links.

Fixes: c1d6dd5d03eb ("wifi: mt76: mt7996: Add mt7996_mcu_teardown_mld_sta rouine")
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20251106064203.1000505-6-shayne.chen@mediatek.com
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>