Revert "final removal of CONFIG_EXPERIMENTAL"

Since we build with wireless-3.8 which still has some dependencies on
CONFIG_EXPERIMENTAL, we need to remove this.

BUG=None
TEST=None

This reverts commit 3d374d09f1.

Change-Id: Ie0e260fe3e67839ee253a19ae794156d1173750d
Signed-off-by: Derek Basehore <dbasehore@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/181550
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Benson Leung <bleung@chromium.org>

init/Kconfig

@@ -28,6 +28,10 @@ config BUILDTIME_EXTABLE_SORT
 
 menu "General setup"
 
+config EXPERIMENTAL
+	bool
+	default y
+
 config BROKEN
 	bool