Wi2Wi GPS module connected through UART

Should be a subnode of the SoC UART it is connected to (serdev).

Required properties:
- compatible:	wi2wi,w2sg0004 or wi2wi,w2sg0084
- on-off-gpio:	the GPIO that controls the module's on-off toggle input

Optional properties:
- lna-suppy:	an (optional) LNA regulator that is enabled together with the GPS receiver

Example:

&uart2 {
	gps: w2sg0004 {
		compatible = "wi2wi,w2sg0004";
		lna-supply = <&vsim>;   /* LNA regulator */
		on-off-gpios = <&gpio5 17 GPIO_ACTIVE_HIGH>;    /* GPIO_145: trigger for turning on/off w2sg0004 */
        };
};
