dm: exynos: Move driver model CONFIGs to Kconfig

Remove driver model CONFIGs from the board config headers and use Kconfig
instead.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/samsung/goni/Kconfig b/board/samsung/goni/Kconfig
index cbbf5a9..2c5d3fc 100644
--- a/board/samsung/goni/Kconfig
+++ b/board/samsung/goni/Kconfig
@@ -12,4 +12,13 @@
 config SYS_CONFIG_NAME
 	default "s5p_goni"
 
+config DM
+	default y if !SPL_BUILD
+
+config DM_GPIO
+	default y if !SPL_BUILD
+
+config DM_SERIAL
+	default y if !SPL_BUILD
+
 endif