* SGM3784 dual flash driver support

Required Properties:
- compatible: Must contain "sgmicro,gsm3784"
- reg: I2C slave address
- enable-gpios: Specifier of the GPIO connected to EN pin
- strobe-gpio: Specifier of the GPIO connected to STROBE pin
- torch-gpio: Specifier of the GPIO connected to GPIO pin,
this pin is for torch mode, if not, will using assist mode.


A discrete LED element connected to the device must be represented by a child
node - see Documentation/devicetree/bindings/leds/common.txt.

Required properties of the LED child node:
- led-max-microamp : see Documentation/devicetree/bindings/leds/common.txt
- flash-max-microamp : see Documentation/devicetree/bindings/leds/common.txt
- flash-max-timeout-us : see Documentation/devicetree/bindings/leds/common.txt

Special properties:
- rockchip,camera-module-index : indicate which camera the flash belongs to.
- rockchip,camera-module-facing : indicate the camera facing.

Example:

&i2c1 {
	...
	sgm3784: sgm3784@30 {
		#address-cells = <1>;
		#size-cells = <0>;
		compatible = "sgmicro,gsm3784";
		reg = <0x30>;
		rockchip,camera-module-index = <0>;
		rockchip,camera-module-facing = "back";
		enable-gpio = <&gpio2 RK_PB4 GPIO_ACTIVE_HIGH>;
		strobe-gpio = <&gpio1 RK_PA3 GPIO_ACTIVE_HIGH>;
		status = "okay";
		sgm3784_led0: led@0 {
			reg = <0x0>;
			led-max-microamp = <299200>;
			flash-max-microamp = <1122000>;
			flash-max-timeout-us = <1600000>;
		};

		sgm3784_led1: led@1 {
			reg = <0x1>;
			led-max-microamp = <299200>;
			flash-max-microamp = <1122000>;
			flash-max-timeout-us = <1600000>;
		};
	};
	...
	ov13850: ov13850@10 {
		...
		flash-leds = <&sgm3784_led0 &sgm3784_led1>;
		...
	};
	...
}