gpio/mxc: use the edge_sel feature if available

Some mxc processors have an edge_sel feature, which allows the IRQ to be
triggered by any edge.

This patch makes use of this feature if available, which skips mxc_flip_edge().

Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Linus Walleij <linus.walleij@stericsson.com>
Acked-by: Sascha Hauer <kernel@pengutronix.de>
Cc: <linux-arm-kernel@lists.infradead.org>
Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/arch/arm/boot/dts/imx51.dtsi b/arch/arm/boot/dts/imx51.dtsi
index bfa65ab..9c95abc 100644
--- a/arch/arm/boot/dts/imx51.dtsi
+++ b/arch/arm/boot/dts/imx51.dtsi
@@ -127,7 +127,7 @@
 			};
 
 			gpio1: gpio@73f84000 {
-				compatible = "fsl,imx51-gpio", "fsl,imx31-gpio";
+				compatible = "fsl,imx51-gpio", "fsl,imx35-gpio";
 				reg = <0x73f84000 0x4000>;
 				interrupts = <50 51>;
 				gpio-controller;
@@ -137,7 +137,7 @@
 			};
 
 			gpio2: gpio@73f88000 {
-				compatible = "fsl,imx51-gpio", "fsl,imx31-gpio";
+				compatible = "fsl,imx51-gpio", "fsl,imx35-gpio";
 				reg = <0x73f88000 0x4000>;
 				interrupts = <52 53>;
 				gpio-controller;
@@ -147,7 +147,7 @@
 			};
 
 			gpio3: gpio@73f8c000 {
-				compatible = "fsl,imx51-gpio", "fsl,imx31-gpio";
+				compatible = "fsl,imx51-gpio", "fsl,imx35-gpio";
 				reg = <0x73f8c000 0x4000>;
 				interrupts = <54 55>;
 				gpio-controller;
@@ -157,7 +157,7 @@
 			};
 
 			gpio4: gpio@73f90000 {
-				compatible = "fsl,imx51-gpio", "fsl,imx31-gpio";
+				compatible = "fsl,imx51-gpio", "fsl,imx35-gpio";
 				reg = <0x73f90000 0x4000>;
 				interrupts = <56 57>;
 				gpio-controller;