Meson SoCs Watchdog timer

Required properties:

- compatible : should be one of
		"amlogic,meson-gxbb-wdt"
		"amlogic,meson-gxl-wdt"
		"amlogic,meson-axg-wdt"
		"amlogic,meson-txl-wdt"
		"amlogic,meson-txlx-wdt"
		"amlogic,meson-g12a-wdt"
		"amlogic,meson-tl1-wdt"
- reg : Specifies base physical address and size of the registers.
- clocks : Should be a phandle to the Watchdog clock source, for GXBB the xtal
	   is the default clock source.

Example:

wdt: watchdog@98d0 {
	compatible = "amlogic,meson-gxbb-wdt";
	reg = <0 0x98d0 0x0 0x10>;
	clocks = <&xtal>;
};

wdt: watchdog@0xffd0f0d0 {
	compatible = "amlogic,meson-g12a-wdt";
	status = "okay";
	reg = <0x0 0xffd0f0d0 0x0 0x10>;
	clock-names = "xtal";
	clocks = <&xtal>;
};

wdt: watchdog@0xffd0f0d0 {
	compatible = "amlogic,meson-tl1-wdt";
	status = "okay";
	reg = <0xffd0f0d0 0x10>;
	clock-names = "xtal";
	clocks = <&xtal>;
};
