[media] dt: bindings: Add binding documentation for sunxi IR controller

This patch adds documentation for Device-Tree bindings for sunxi IR
controller.
Signed-off-by: Alexander Bersenev <bay@hackerdom.ru>
Signed-off-by: Alexsey Shestacov <wingrime@linux-sunxi.org>
[hdegoede@redhat.com: Changed compatible to sun4i-a10-ir]
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

Documentation/devicetree/bindings/media/sunxi-ir.txt

+Device-Tree bindings for SUNXI IR controller found in sunXi SoC family
+
+Required properties:
+- compatible	    : should be "allwinner,sun4i-a10-ir";
+- clocks	    : list of clock specifiers, corresponding to
+		      entries in clock-names property;
+- clock-names	    : should contain "apb" and "ir" entries;
+- interrupts	    : should contain IR IRQ number;
+- reg		    : should contain IO map address for IR.
+
+Optional properties:
+- linux,rc-map-name : Remote control map name.
+
+Example:
+
+ir0: ir@01c21800 {
+	compatible = "allwinner,sun4i-a10-ir";
+	clocks = <&apb0_gates 6>, <&ir0_clk>;
+	clock-names = "apb", "ir";
+	interrupts = <0 5 1>;
+	reg = <0x01C21800 0x40>;
+	linux,rc-map-name = "rc-rc6-mce";
+};