dm: exynos: dts: Use GPIO bank phandles for GPIOs

U-Boot now supports using GPIOs using bank phandles instead of global
numbers. Update the exynos device tree files to use this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Minkyu Kang <mk7.kang@samsung.com>
diff --git a/arch/arm/dts/exynos5.dtsi b/arch/arm/dts/exynos5.dtsi
index e539068..238acb8 100644
--- a/arch/arm/dts/exynos5.dtsi
+++ b/arch/arm/dts/exynos5.dtsi
@@ -6,6 +6,7 @@
  */
 
 #include "skeleton.dtsi"
+#include <dt-bindings/gpio/gpio.h>
 
 / {
 	compatible = "samsung,exynos5";
@@ -247,7 +248,4 @@
 		u-boot,dm-pre-reloc;
 		id = <3>;
 	};
-
-	gpio: gpio {
-	};
 };