dt-bindings: interrupt-controller: Document RDA8810PL intc

Document interrupt controller in RDA Micro RDA8810PL SoC.
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

Documentation/devicetree/bindings/interrupt-controller/rda,8810pl-intc.txt

+RDA Micro RDA8810PL Interrupt Controller
+
+The interrupt controller in RDA8810PL SoC is a custom interrupt controller
+which supports up to 32 interrupts.
+
+Required properties:
+
+- compatible: Should be "rda,8810pl-intc".
+- reg: Specifies base physical address of the registers set.
+- interrupt-controller: Identifies the node as an interrupt controller.
+- #interrupt-cells: Specifies the number of cells needed to encode an
+  interrupt source. The value shall be 2.
+
+The interrupt sources are as follows:
+
+ID	Name
+------------
+0:	PULSE_DUMMY
+1:	I2C
+2:	NAND_NFSC
+3:	SDMMC1
+4:	SDMMC2
+5:	SDMMC3
+6:	SPI1
+7:	SPI2
+8:	SPI3
+9:	UART1
+10:	UART2
+11:	UART3
+12:	GPIO1
+13:	GPIO2
+14:	GPIO3
+15:	KEYPAD
+16:	TIMER
+17:	TIMEROS
+18:	COMREG0
+19:	COMREG1
+20:	USB
+21:	DMC
+22:	DMA
+23:	CAMERA
+24:	GOUDA
+25:	GPU
+26:	VPU_JPG
+27:	VPU_HOST
+28:	VOC
+29:	AUIFC0
+30:	AUIFC1
+31:	L2CC
+
+Example:
+		apb@20800000 {
+			compatible = "simple-bus";
+			...
+			intc: interrupt-controller@0 {
+				compatible = "rda,8810pl-intc";
+				reg = <0x0 0x1000>;
+				interrupt-controller;
+				#interrupt-cells = <2>;
+			};
+		};