ARM: DT: bcm21664: Device tree bindings

Add binding documents for the Broadcom BCM21664 SoC.
Signed-off-by: NMarkus Mayer <markus.mayer@linaro.org>
Signed-off-by: NMatt Porter <mporter@linaro.org>

Documentation/devicetree/bindings/arm/bcm/bcm21664.txt

+Broadcom BCM21664 device tree bindings
+--------------------------------------
+
+This document describes the device tree bindings for boards with the BCM21664
+SoC.
+
+Required root node property:
+  - compatible: brcm,bcm21664
+
+Example:
+	/ {
+		model = "BCM21664 SoC";
+		compatible = "brcm,bcm21664";
+		[...]
+	}

Documentation/devicetree/bindings/arm/bcm/kona-resetmgr.txt

+Broadcom Kona Family Reset Manager
+----------------------------------
+
+The reset manager is used on the Broadcom BCM21664 SoC.
+
+Required properties:
+  - compatible: brcm,bcm21664-resetmgr
+  - reg: memory address & range
+
+Example:
+	brcm,resetmgr@35001f00 {
+		compatible = "brcm,bcm21664-resetmgr";
+		reg = <0x35001f00 0x24>;
+	};