Renesas Watchdog Timer (WDT) Controller

Required properties:
 - compatible : Must be "renesas,<soctype>-wdt", followed by a generic
		fallback compatible string when compatible with the generic
		version.
	       Examples with soctypes are:
		 - "renesas,r8a7743-wdt" (RZ/G1M)
		 - "renesas,r8a7744-wdt" (RZ/G1N)
		 - "renesas,r8a7745-wdt" (RZ/G1E)
		 - "renesas,r8a77470-wdt" (RZ/G1C)
		 - "renesas,r8a774a1-wdt" (RZ/G2M)
		 - "renesas,r8a774c0-wdt" (RZ/G2E)
	         - "renesas,r8a7790-wdt" (R-Car H2)
	         - "renesas,r8a7791-wdt" (R-Car M2-W)
	         - "renesas,r8a7792-wdt" (R-Car V2H)
	         - "renesas,r8a7793-wdt" (R-Car M2-N)
	         - "renesas,r8a7794-wdt" (R-Car E2)
	         - "renesas,r8a7795-wdt" (R-Car H3)
	         - "renesas,r8a7796-wdt" (R-Car M3-W)
		 - "renesas,r8a77965-wdt" (R-Car M3-N)
	         - "renesas,r8a77970-wdt" (R-Car V3M)
	         - "renesas,r8a77990-wdt" (R-Car E3)
	         - "renesas,r8a77995-wdt" (R-Car D3)
	         - "renesas,r7s72100-wdt" (RZ/A1)
	         - "renesas,r7s9210-wdt"  (RZ/A2)
		The generic compatible string must be:
		 - "renesas,rza-wdt" for RZ/A
		 - "renesas,rcar-gen2-wdt" for R-Car Gen2 and RZ/G1
		 - "renesas,rcar-gen3-wdt" for R-Car Gen3 and RZ/G2

- reg : Should contain WDT registers location and length
- clocks : the clock feeding the watchdog timer.

Optional properties:
- timeout-sec : Contains the watchdog timeout in seconds
- power-domains : the power domain the WDT belongs to
- interrupts: Some WDTs have an interrupt when used in interval timer mode

Examples:

	wdt0: watchdog@e6020000 {
		compatible = "renesas,r8a7795-wdt", "renesas,rcar-gen3-wdt";
		reg = <0 0xe6020000 0 0x0c>;
		clocks = <&cpg CPG_MOD 402>;
		power-domains = <&cpg>;
		timeout-sec = <60>;
	};
