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

All the UniPhier boards have switch to Driver Model.
"select DM" is better than default value in each 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 afd770c..1c90d17 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -761,6 +761,9 @@
 	select SUPPORT_SPL
 	select SPL
 	select OF_CONTROL
+	select DM
+	select DM_SERIAL
+	select DM_I2C
 
 endchoice