* ROHM BH1730FVC ambient light sensor

nvs_ drivers use the NVidia Sensor (NVS) framework.
See the nvs.txt documentation for NVS DT capabilities.

Required properties:
- compatible: must be "rohm,bh1730fvc"
- reg: i2c address of the device. It should be 0x29.

Optional properties:
- status: set to "ok" or "okay" for normal operation.  Set to anything else
	  to unload the driver without ever communicating with the device.
  Note: The "anything else" above is typically "disabled".
	Since the driver will unload without communicating with the device, the
	device will be left in its POR state.
- vdd-supply: regulator supply for the chip vcc
- vid-supply: regulator supply for the chip dvi
  Note: This is required if the driver is to control the regulator.
- bh1730fvc-lux-coeff-size: array size of bh1730fvc-lux-coeff.
- bh1730fvc-lux-coeff: Lux calculation coefficient table. See the note.
- bh1730fvc-lux-resolution: See the note.
- bh1730fvc-lux-multiplier: See the note.
  Note: If lux coefficient data is not present, default calculation table is used.
        If present, lux calculation is done with following equation.
        Let following is set in dt:
            bh1730fvc-lux-coeff-size = <5>;
            bh1730fvc-lux-coeff =   < 500 5002 7502>,
                                    < 754 2250 2000>,
                                    <1029 1999 1667>,
                                    <1373  884  583>,
                                    <1879  309  165>;
            bh1730fvc-lux-resolution = <1000>;
            bh1730fvc-lux-multiplier = <360>;
        Then lux is calculated with this equation:
            if (data1 * 1000 / data0 < 500)
                 lux = 5002 * data0 - 7502 * data1
            else if (data1 * 1000 / data0 < 754)
                 lux = 2250 * data0 - 2000 * data1
            else if (data1 * 1000 / data0 < 1029)
                 lux = 1999 * data0 - 1667 * data1
            else if (data1 * 1000 / data0 < 1373)
                 lux = 884 * data0 - 583 * data1
            else if (data1 * 1000 / data0 < 1879)
                 lux = 309 * data0 - 165 * data1
            lux = lux * 360 / (gain * itime_us)

Example:
                bh1730fvc@29 {
                        compatible = "rohm,bh1730fvc";
                        reg = <0x29>;
                        bh1730fvc-lux-coeff-size = <5>;
                        bh1730fvc-lux-coeff =   < 500 5002 7502>,
                                                < 754 2250 2000>,
                                                <1029 1999 1667>,
                                                <1373  884  583>,
                                                <1879  309  165>;
                        bh1730fvc-lux-resolution = <1000>;
                        bh1730fvc-lux-multiplier = <360>;
                };