ramips: export slic IRQ line in dwr-512

The DWR-512 embeds the hw slic device si3210. This device have the IRQ line
attached to the gpio1. This patch export the gpio1 with proper name and
parameters to the sysfs.

Signed-off-by: Giuseppe Lippolis <giu.lippolis@gmail.com>

target/linux/ramips/dts/DWR-512-B.dts

@@ -61,6 +61,10 @@
 		compatible = "gpio-export";
 		#size-cells = <0>;
 
+		slic_int {
+			gpio-export,name = "slic_int";
+			gpios = <&gpio0 1 GPIO_ACTIVE_LOW>;
+		};
 		modem3g_enable {
 			gpio-export,name = "modem3g_enable";
 			gpio-export,output = <1>;