Bindings for MEN A21 Watchdog device connected to GPIO lines

Required properties:
- compatible: "men,a021-wdt"
- gpios: Specifies the pins that control the Watchdog, order:
  1: Watchdog enable
  2: Watchdog fast-mode
  3: Watchdog trigger
  4: Watchdog reset cause bit 0
  5: Watchdog reset cause bit 1
  6: Watchdog reset cause bit 2

Optional properties:
- None

Example:
	watchdog {
		compatible ="men,a021-wdt";
		gpios = <&gpio3 9  1	/* WD_EN */
			 &gpio3 10 1	/* WD_FAST */
			 &gpio3 11 1	/* WD_TRIG */
			 &gpio3 6  1	/* RST_CAUSE[0] */
			 &gpio3 7  1	/* RST_CAUSE[1] */
			 &gpio3 8  1>;	/* RST_CAUSE[2] */
	};
