ARM: cm_fx6: use "select" instead of default value in defconfig

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index af2d4f4..3702bb0 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -630,6 +630,9 @@
 	bool "Support cm_fx6"
 	select CPU_V7
 	select SUPPORT_SPL
+	select DM
+	select DM_SERIAL
+	select DM_GPIO
 
 config TARGET_SOCFPGA_ARRIA5
 	bool "Support socfpga_arria5"
diff --git a/configs/cm_fx6_defconfig b/configs/cm_fx6_defconfig
index f10a5c2..c83a0e8 100644
--- a/configs/cm_fx6_defconfig
+++ b/configs/cm_fx6_defconfig
@@ -2,6 +2,3 @@
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=arch/arm/imx-common/spl_sd.cfg,MX6QDL,SPL"
 CONFIG_ARM=y
 CONFIG_TARGET_CM_FX6=y
-CONFIG_DM=y
-CONFIG_DM_GPIO=y
-CONFIG_DM_SERIAL=y