ARM: dts: clps711x: Add bindings documentation for CLPS711X irqchip driver

Add OF document for Cirrus Logic CLPS711X irqchip driver.
Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/interrupt-controller/cirrus,clps711x-intc.txt

+Cirrus Logic CLPS711X Interrupt Controller
+
+Required properties:
+
+- compatible: Should be "cirrus,clps711x-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 1.
+
+The interrupt sources are as follows:
+ID	Name	Description
+---------------------------
+1:	BLINT	Battery low (FIQ)
+3:	MCINT	Media changed (FIQ)
+4:	CSINT	CODEC sound
+5:	EINT1	External 1
+6:	EINT2	External 2
+7:	EINT3	External 3
+8:	TC1OI	TC1 under flow
+9:	TC2OI	TC2 under flow
+10:	RTCMI	RTC compare match
+11:	TINT	64Hz tick
+12:	UTXINT1	UART1 transmit FIFO half empty
+13:	URXINT1	UART1 receive FIFO half full
+14:	UMSINT	UART1 modem status changed
+15:	SSEOTI	SSI1 end of transfer
+16:	KBDINT	Keyboard
+17:	SS2RX	SSI2 receive FIFO half or greater full
+18:	SS2TX	SSI2 transmit FIFO less than half empty
+28:	UTXINT2	UART2 transmit FIFO half empty
+29:	URXINT2	UART2 receive FIFO half full
+32:	DAIINT	DAI interface (FIQ)
+
+Example:
+	intc: interrupt-controller {
+		compatible = "cirrus,clps711x-intc";
+		reg = <0x80000000 0x4000>;
+		interrupt-controller;
+		#interrupt-cells = <1>;
+	};