cros: exynos: add cros-ec device nodes to exynos5250-snow.dts

This patch adds cros-ec related device nodes to exynos5250-snow.dts.
It also adds a gpio node to exynos5250.dtsi.

Signed-off-by: Hung-ying Tyan <tyanh@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/dts/exynos5250.dtsi b/arch/arm/dts/exynos5250.dtsi
index cee4fe8..2d6dfff 100644
--- a/arch/arm/dts/exynos5250.dtsi
+++ b/arch/arm/dts/exynos5250.dtsi
@@ -202,4 +202,6 @@
 		interrupts = <0 78 0>;
 	};
 
+	gpio: gpio {
+	};
 };