Bluetooth: btusb: Add support using different nvm for variant WCN6855 controller

the RF performance of wcn6855 soc chip from different foundries will be
difference, so we should use different nvm to configure them.

Signed-off-by: Tim Jiang <tjiang@codeaurora.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>