WCN3991 supports transparent WBS (host encoded mSBC). Add a flag to the
device match data to show WBS is supported.

This requires the matching firmware for WCN3991 in linux-firmware:
        1a8b0dc00f77 (qca: Enable transparent WBS for WCN3991)
Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>