Texas Instruments DRA7xx Radio Helper

Radio Helper is a dummy device on top of the devices such as McAsp
that needs to be configured for Radio playback.
The corresponding platform driver configures these devices as
required.

Top node:
Required properties:
 - compatible: "ti,dra7xx_radio"
 - gpios: List of the gpios that needs to be configured

child nodes:
 - compatible: "ti,dra7xx_radio_subdev"
 - ti,hwmods: Name of the hwmod associated to the underlying devices
 - status: Device status
