kbuild: add hint about __refdata to modpost

As requested by Guennadi Liakhovetski

Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 94e71ef..4522948 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1196,7 +1196,7 @@
 		"The variable %s references\n"
 		"the %s %s%s%s\n"
 		"If the reference is valid then annotate the\n"
-		"variable with __init* (see linux/init.h) "
+		"variable with __init* or __refdata (see linux/init.h) "
 		"or name the variable:\n",
 		fromsym, to, sec2annotation(tosec), tosym, to_p);
 		while (*s)