dt-bindings: net: Add generic Bluetooth controller

Bluetooth controllers share the common local-bd-address property.
Add a generic YAML schema to replace bluetooth.txt for those.

Signed-off-by: Sven Peter <sven@svenpeter.dev>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>