[S390] Get rid of a lot of sparse warnings.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/net/claw.c b/drivers/s390/net/claw.c
index 95f4e10..4313f31 100644
--- a/drivers/s390/net/claw.c
+++ b/drivers/s390/net/claw.c
@@ -121,7 +121,7 @@
 #define DEBUG
 #endif
 
- char debug_buffer[255];
+static char debug_buffer[255];
 /**
  * Debug Facility Stuff
  */