Bluetooth: btusb: Enable MSFT extension for Mediatek Chip (MT7921)

The Mdiatek MT7921(7961) support MSFT HCI extensions, we are using
0xFD30 for VsMsftOpCode.

Signed-off-by: mark-yw.chen <mark-yw.chen@mediatek.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>