[Bluetooth] Support the case when headset falls back to SCO link

When trying to establish an eSCO link between two devices then it can
happen that the remote device falls back to a SCO link. Currently this
case is not handled correctly and the message dispatching will break
since it is looking for eSCO packets. So in case the configured link
falls back to SCO overwrite the link type with the correct value.

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