wifi: mt76: mt7996: rework mt7996_rx_get_wcid to support MLO

wifi: mt76: mt7996: rework mt7996_rx_get_wcid to support MLO

The wcid idx and band idx in the TXS are sometimes mismatched since the
FW will select a transmission link according to a private algorithm.
That is, the wcid idx in the TXS would be the one registered by the
driver rather than the actual wcid idx used during transmission.
However, the band idx in the TXS is the band select for transmission.
Therefore, we should get the driver-registered wcid in order
to notify the driver the packet has been acked; otherwise,
the driver will be unable to match the transmitted packet and its TXS.
This is a preliminary patch to enable MLO for MT7996 driver.

Co-developed-by: Bo Jiao <Bo.Jiao@mediatek.com>
Signed-off-by: Bo Jiao <Bo.Jiao@mediatek.com>
Co-developed-by: Peter Chiu <chui-hao.chiu@mediatek.com>
Signed-off-by: Peter Chiu <chui-hao.chiu@mediatek.com>
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Co-developed-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20250312-b4-mt7996-mlo-p2-v1-6-015b3d6fd928@kernel.org
Signed-off-by: Felix Fietkau <nbd@nbd.name>