media: dt: bindings: Add binding for tango HW IR decoder

Add DT binding for the HW IR decoder embedded in SMP86xx/SMP87xx.
Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Acked-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/tango-ir.txt

+Sigma Designs Tango IR NEC/RC-5/RC-6 decoder (SMP86xx and SMP87xx)
+
+Required properties:
+
+- compatible: "sigma,smp8642-ir"
+- reg: address/size of NEC+RC5 area, address/size of RC6 area
+- interrupts: spec for IR IRQ
+- clocks: spec for IR clock (typically the crystal oscillator)
+
+Optional properties:
+
+- linux,rc-map-name: see Documentation/devicetree/bindings/media/rc.txt
+
+Example:
+
+	ir@10518 {
+		compatible = "sigma,smp8642-ir";
+		reg = <0x10518 0x18>, <0x105e0 0x1c>;
+		interrupts = <21 IRQ_TYPE_EDGE_RISING>;
+		clocks = <&xtal>;
+	};