UniPhier watchdog timer controller

This UniPhier watchdog timer controller must be under sysctrl node.

Required properties:
- compatible: should be "socionext,uniphier-wdt"

Example:

	sysctrl@61840000 {
		compatible = "socionext,uniphier-ld11-sysctrl",
			     "simple-mfd", "syscon";
		reg = <0x61840000 0x4000>;

		watchdog {
			compatible = "socionext,uniphier-wdt";
		}

		other nodes ...
	};