Meson SoCs Watchdog timer

Required properties:

- compatible : depending on the SoC this should be one of:
	"amlogic,meson6-wdt" on Meson6 SoCs
	"amlogic,meson8-wdt" and "amlogic,meson6-wdt" on Meson8 SoCs
	"amlogic,meson8b-wdt" on Meson8b SoCs
	"amlogic,meson8m2-wdt" and "amlogic,meson8b-wdt" on Meson8m2 SoCs
- reg : Specifies base physical address and size of the registers.

Optional properties:
- timeout-sec: contains the watchdog timeout in seconds.

Example:

wdt: watchdog@c1109900 {
	compatible = "amlogic,meson6-wdt";
	reg = <0xc1109900 0x8>;
	timeout-sec = <10>;
};