[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/net/ctcm_sysfs.c b/drivers/s390/net/ctcm_sysfs.c
index 8305319..650aec1 100644
--- a/drivers/s390/net/ctcm_sysfs.c
+++ b/drivers/s390/net/ctcm_sysfs.c
@@ -159,7 +159,7 @@
 	return count;
 }
 
-const char *ctcm_type[] = {
+static const char *ctcm_type[] = {
 	"not a channel",
 	"CTC/A",
 	"FICON channel",