ARM: dts: imx: update #interrupt-cells for gpio nodes

Change the value of #interrupt-cells of gpio nodes from 1 to 2, so that
the gpio irq type can be specified in device tree.  Also update binding
document to make it clear.

Reported-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
diff --git a/arch/arm/boot/dts/imx6q.dtsi b/arch/arm/boot/dts/imx6q.dtsi
index 16a3884..bf88fb7 100644
--- a/arch/arm/boot/dts/imx6q.dtsi
+++ b/arch/arm/boot/dts/imx6q.dtsi
@@ -283,7 +283,7 @@
 				gpio-controller;
 				#gpio-cells = <2>;
 				interrupt-controller;
-				#interrupt-cells = <1>;
+				#interrupt-cells = <2>;
 			};
 
 			gpio2: gpio@020a0000 {
@@ -293,7 +293,7 @@
 				gpio-controller;
 				#gpio-cells = <2>;
 				interrupt-controller;
-				#interrupt-cells = <1>;
+				#interrupt-cells = <2>;
 			};
 
 			gpio3: gpio@020a4000 {
@@ -303,7 +303,7 @@
 				gpio-controller;
 				#gpio-cells = <2>;
 				interrupt-controller;
-				#interrupt-cells = <1>;
+				#interrupt-cells = <2>;
 			};
 
 			gpio4: gpio@020a8000 {
@@ -313,7 +313,7 @@
 				gpio-controller;
 				#gpio-cells = <2>;
 				interrupt-controller;
-				#interrupt-cells = <1>;
+				#interrupt-cells = <2>;
 			};
 
 			gpio5: gpio@020ac000 {
@@ -323,7 +323,7 @@
 				gpio-controller;
 				#gpio-cells = <2>;
 				interrupt-controller;
-				#interrupt-cells = <1>;
+				#interrupt-cells = <2>;
 			};
 
 			gpio6: gpio@020b0000 {
@@ -333,7 +333,7 @@
 				gpio-controller;
 				#gpio-cells = <2>;
 				interrupt-controller;
-				#interrupt-cells = <1>;
+				#interrupt-cells = <2>;
 			};
 
 			gpio7: gpio@020b4000 {
@@ -343,7 +343,7 @@
 				gpio-controller;
 				#gpio-cells = <2>;
 				interrupt-controller;
-				#interrupt-cells = <1>;
+				#interrupt-cells = <2>;
 			};
 
 			kpp@020b8000 {