Bluetooth: Allow SCO audio with Asus WL-BTD202 dongle

This patch allows the Asus WL-BTD202 dongle to be used with a mono
headset without having to specify "options btusb force_scofix=1".

Based on a patch from Guillaume Bedot <littletux@zarb.org>

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>