dt-binding: iio: add NPCM ADC reset support

- compatible: "nuvoton,npcm750-adc" for the NPCM7XX BMC.

- reg: specifies physical base address and size of the registers.

- interrupts: Contain the ADC interrupt with flags for falling edge.

- resets : phandle to the reset control for this device.

Optional properties:

- clocks: phandle of ADC reference clock, in case the clock is not

	reg = <0xf000c000 0x8>;

	interrupts = <GIC_SPI 0 IRQ_TYPE_LEVEL_HIGH>;

	clocks = <&clk NPCM7XX_CLK_ADC>;

	resets = <&rstc NPCM7XX_RESET_IPSRST1 NPCM7XX_RESET_ADC>;

};