ARM: am335x: select DM_GPIO

We are supposed to not add config entries with only "default y"
in board/SoC Kconfig files.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 37fee43..e63309a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -459,6 +459,7 @@
 	select CPU_V7
 	select SUPPORT_SPL
 	select DM
+	select DM_GPIO
 	select DM_SERIAL
 
 config TARGET_BAV335X