* DW9800W vcm driver support

Required Properties:
- compatible: Must contain "chipnext,cn3927v"
- reg: I2C slave address

Optional Properties:
- rockchip,vcm-max-current: max output current, unit: mA.
- rockchip,vcm-start-current: starting current.
- rockchip,vcm-rated-current: rate current.
- rockchip,vcm-step-mode: 0 SAC2 mode,1 SAC3 mode,2 SAC4 mode,3 SAC5 mode,4 Direct mode,5 LSC mode.
- rockchip,vcm-t-src : SACT[5:0],  Tvib = 6.3ms + SACT[5:0]*0.1ms, recommend: 10ms.
- rockchip,vcm-t-div : 0 Tvibx2(double),1 Tvibx1(default),2 Tvibx1/2(half),3 Tvibx1/4(quarter),4 Tvibx8,5 Tvibx4,

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

Example:

&i2c4 {
	...
	dw9800w: dw9800w@c {
		compatible = "dongwoon,dw9800w";
		status = "okay";
		reg = <0x0c>;
		rockchip,vcm-max-current = <100>;
		rockchip,vcm-start-current = <20>;
		rockchip,vcm-rated-current = <80>;
		rockchip,vcm-step-mode = <1>;
		rockchip,vcm-t-src = <0x25>;
		rockchip,vcm-t-div = <1>;
		rockchip,camera-module-index = <0>;
		rockchip,camera-module-facing = "back";
	};

	...
	imx586: s5kjn1@1a {
		...
		lens-focus = <&dw9800w>;
		...
	};
	...
}