Nuvoton NPCM Watchdog

Nuvoton NPCM timer module provides five 24-bit timer counters, and a watchdog.
The watchdog supports a pre-timeout interrupt that fires 10ms before the
expiry.

Required properties:
- compatible      : "nuvoton,npcm750-wdt" for NPCM750 (Poleg), or
                    "nuvoton,wpcm450-wdt" for WPCM450 (Hermon).
- reg             : Offset and length of the register set for the device.
- interrupts      : Contain the timer interrupt with flags for
                    falling edge.

Required clocking property, have to be one of:
- clocks          : phandle of timer reference clock.
- clock-frequency : The frequency in Hz of the clock that drives the NPCM7xx
                    timer (usually 25000000).

Optional properties:
- timeout-sec : Contains the watchdog timeout in seconds

Example:

timer@f000801c {
    compatible = "nuvoton,npcm750-wdt";
    interrupts = <GIC_SPI 47 IRQ_TYPE_LEVEL_HIGH>;
    reg = <0xf000801c 0x4>;
    clocks = <&clk NPCM7XX_CLK_TIMER>;
};