* Silicon Labs FM Radio transmitter

The Silicon Labs Si4713 is an FM radio transmitter with receive power scan
supporting 76-108 MHz. It includes an RDS encoder and has both, a stereo-analog
and a digital interface, which supports I2S, left-justified and a custom
DSP-mode format. It is programmable through an I2C interface.

Required Properties:
- compatible: Should contain "silabs,si4713"
- reg: the I2C address of the device

Optional Properties:
- interrupts-extended: Interrupt specifier for the chips interrupt
- reset-gpios: GPIO specifier for the chips reset line
- vdd-supply: phandle for Vdd regulator
- vio-supply: phandle for Vio regulator

Example:

&i2c2 {
        fmtx: si4713@63 {
                compatible = "silabs,si4713";
                reg = <0x63>;

                interrupts-extended = <&gpio2 21 IRQ_TYPE_EDGE_FALLING>; /* 53 */
                reset-gpios = <&gpio6 3 GPIO_ACTIVE_HIGH>; /* 163 */
                vio-supply = <&vio>;
                vdd-supply = <&vaux1>;
        };
};