dt-bindings: interrupt-controller: Update csky mpintc

Add trigger type setting for csky,mpintc. The driver also could
support #interrupt-cells <1> and it wouldn't invalidate existing
DTs. Here we only show the complete format.
Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reviewed-by: Rob Herring <robh+dt@kernel.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>

Documentation/devicetree/bindings/interrupt-controller/csky,mpintc.txt

@@ -6,11 +6,16 @@ C-SKY Multi-processors Interrupt Controller is designed for ck807/ck810/ck860
 SMP soc, and it also could be used in non-SMP system.
 
 Interrupt number definition:
-
   0-15  : software irq, and we use 15 as our IPI_IRQ.
  16-31  : private  irq, and we use 16 as the co-processor timer.
  31-1024: common irq for soc ip.
 
+Interrupt triger mode: (Defined in dt-bindings/interrupt-controller/irq.h)
+ IRQ_TYPE_LEVEL_HIGH (default)
+ IRQ_TYPE_LEVEL_LOW
+ IRQ_TYPE_EDGE_RISING
+ IRQ_TYPE_EDGE_FALLING
+
 =============================
 intc node bindings definition
 =============================
@@ -26,15 +31,22 @@ intc node bindings definition
 	- #interrupt-cells
 		Usage: required
 		Value type: <u32>
-		Definition: must be <1>
+		Definition: <2>
 	- interrupt-controller:
 		Usage: required
 
-Examples:
+Examples: ("interrupts = <irq_num IRQ_TYPE_XXX>")
 ---------
+#include <dt-bindings/interrupt-controller/irq.h>
 
 	intc: interrupt-controller {
 		compatible = "csky,mpintc";
-		#interrupt-cells = <1>;
+		#interrupt-cells = <2>;
 		interrupt-controller;
 	};
+
+	device: device-example {
+		...
+		interrupts = <34 IRQ_TYPE_EDGE_RISING>;
+		interrupt-parent = <&intc>;
+	};