mt76: mt7615: add starec operating flow for firmware v2

Add fw_ver in mt7615_dev to check firmware version, and adjust
mt7615_mcu_send_sta_rec() to adapt firmware v2 changes.

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Tested-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>