dm: test: Add a Kconfig file

Add a file to control driver model test features.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/test/Kconfig b/test/Kconfig
new file mode 100644
index 0000000..1fb1716
--- /dev/null
+++ b/test/Kconfig
@@ -0,0 +1 @@
+source "test/dm/Kconfig"