[media] media: rc: meson: document device tree bindings

This adds binding documentation for the infrared remote control
receiver available in Amlogic Meson SoCs.
Signed-off-by: NBeniamino Galvani <b.galvani@gmail.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

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

+* Amlogic Meson IR remote control receiver
+
+Required properties:
+ - compatible	: should be "amlogic,meson6-ir"
+ - reg		: physical base address and length of the device registers
+ - interrupts	: a single specifier for the interrupt from the device
+
+Example:
+
+	ir-receiver@c8100480 {
+		compatible= "amlogic,meson6-ir";
+		reg = <0xc8100480 0x20>;
+		interrupts = <0 15 1>;
+	};