kconfig: add blank Kconfig files

This would be useful to start moving various config options.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
diff --git a/common/Kconfig b/common/Kconfig
new file mode 100644
index 0000000..5ae7190
--- /dev/null
+++ b/common/Kconfig
@@ -0,0 +1,4 @@
+menu "Command line interface"
+	depends on !SPL_BUILD
+
+endmenu