dm: exynos: Tidy up GPIO headers

The wrong header is being included, thus requiring the code to re-declare
the generic GPIO interface in each GPIO header.

Fix this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/samsung/goni/goni.c b/board/samsung/goni/goni.c
index 5f76be3..4cee78b 100644
--- a/board/samsung/goni/goni.c
+++ b/board/samsung/goni/goni.c
@@ -7,7 +7,7 @@
  */
 
 #include <common.h>
-#include <asm/arch/gpio.h>
+#include <asm/gpio.h>
 #include <asm/arch/mmc.h>
 #include <power/pmic.h>
 #include <usb/s3c_udc.h>