Bluetooth: btusb: Add flag to define wideband speech capability

This change adds a new flag to define a controller's wideband speech
capability.  This is required since no reliable over HCI mechanism
exists to query the controller and driver's compatibility with
wideband speech.

Signed-off-by: Alain Michaud <alainm@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>