Device-Tree bindings for dummy Bluetooth SCO codec

Required properties:
	- compatible: should be "linux,bt-sco-audio".

CODEC output pins:
  * TX

CODEC input pins:
  * RX

Example node:

	bt_sco_audio: bt_sco_audio@0 {
		compatible = "linux,bt-sco-audio";
		status = "okay";
	};
