s390/css: export css_sched_sch_todo

Allow subchannel drivers build as a module to schedule subchannel work.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 21908e6..b4d572f 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -445,6 +445,7 @@
 		put_device(&sch->dev);
 	}
 }
+EXPORT_SYMBOL_GPL(css_sched_sch_todo);
 
 static void css_sch_todo(struct work_struct *work)
 {