Bluetooth: btqcomsmd: retrieve BD address from DT property

Retrieve BD address from the local-bd-address property.
This address must be unique and is usually added in the DT
by the bootloader which has access to the provisioned data.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>