[S390] sparse: fix sparse static warnings

Make functions and data static to avoid sparse warnings.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/cio/qdio_thinint.c b/drivers/s390/cio/qdio_thinint.c
index 8c1f412..9d1e7ef 100644
--- a/drivers/s390/cio/qdio_thinint.c
+++ b/drivers/s390/cio/qdio_thinint.c
@@ -29,7 +29,7 @@
 
 /* list of thin interrupt input queues */
 static LIST_HEAD(tiq_list);
-DEFINE_MUTEX(tiq_list_lock);
+static DEFINE_MUTEX(tiq_list_lock);
 
 /* adapter local summary indicator */
 static u8 *tiqdio_alsi;