Zodiac Inflight Innovations RAVE Supervisory Processor Watchdog Bindings

RAVE SP watchdog device is a "MFD cell" device corresponding to
watchdog functionality of RAVE Supervisory Processor. It is expected
that its Device Tree node is specified as a child of the node
corresponding to the parent RAVE SP device (as documented in
Documentation/devicetree/bindings/mfd/zii,rave-sp.txt)

Required properties:

- compatible: Depending on wire protocol implemented by RAVE SP
  firmware, should be one of:
	- "zii,rave-sp-watchdog"
	- "zii,rave-sp-watchdog-legacy"

Optional properties:

- wdt-timeout:	Two byte nvmem cell specified as per
		Documentation/devicetree/bindings/nvmem/nvmem.txt

Example:

	rave-sp {
		compatible = "zii,rave-sp-rdu1";
		current-speed = <38400>;

		eeprom {
			wdt_timeout: wdt-timeout@8E {
				reg = <0x8E 2>;
			};
		};

		watchdog {
			compatible = "zii,rave-sp-watchdog";
			nvmem-cells = <&wdt_timeout>;
			nvmem-cell-names = "wdt-timeout";
		};
	}

