[S390] Avoid sparse warnings.

Monthly sparse warning avoidance patch. Sigh.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/drivers/s390/scsi/zfcp_dbf.c b/drivers/s390/scsi/zfcp_dbf.c
index d8191d1..5f32124 100644
--- a/drivers/s390/scsi/zfcp_dbf.c
+++ b/drivers/s390/scsi/zfcp_dbf.c
@@ -478,7 +478,7 @@
 	NULL
 };
 
-void
+static void
 _zfcp_san_dbf_event_common_ct(const char *tag, struct zfcp_fsf_req *fsf_req,
 			      u32 s_id, u32 d_id, void *buffer, int buflen)
 {