wifi: mt76: mt7925: update mt7925_mcu_set_timing for MLO

Set the BSS index from the per-linked BSS for the firmware to identify
which link the command is operating on.

Co-developed-by: Ming Yen Hsieh <mingyen.hsieh@mediatek.com>
Signed-off-by: Ming Yen Hsieh <mingyen.hsieh@mediatek.com>
Co-developed-by: Deren Wu <deren.wu@mediatek.com>
Signed-off-by: Deren Wu <deren.wu@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Link: https://patch.msgid.link/dde970c748586d03fbecbccb10cb9903284719aa.1720248331.git.sean.wang@kernel.org


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