media: dt: bindings: Update binding documentation for sunxi IR controller

This patch updates documentation for Device-Tree bindings for sunxi IR
controller and adds the new optional property for the base clock
frequency.

Signed-off-by: Philipp Rossak <embed3d@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

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

@@ -11,6 +11,8 @@ Required properties:
 Optional properties:
 - linux,rc-map-name: see rc.txt file in the same directory.
 - resets : phandle + reset specifier pair
+- clock-frequency  : IR Receiver clock frequency, in Hertz. Defaults to 8 MHz
+		     if missing.
 
 Example:
 
@@ -18,6 +20,7 @@ ir0: ir@1c21800 {
 	compatible = "allwinner,sun4i-a10-ir";
 	clocks = <&apb0_gates 6>, <&ir0_clk>;
 	clock-names = "apb", "ir";
+	clock-frequency = <3000000>;
 	resets = <&apb0_rst 1>;
 	interrupts = <0 5 1>;
 	reg = <0x01C21800 0x40>;