[S390] Fix 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/char/con3215.c b/drivers/s390/char/con3215.c
index f25c6d1..2fa566f 100644
--- a/drivers/s390/char/con3215.c
+++ b/drivers/s390/char/con3215.c
@@ -693,7 +693,7 @@
 				       GFP_KERNEL|GFP_DMA);
 	if (raw->buffer == NULL) {
 		spin_lock(&raw3215_device_lock);
-		raw3215[line] = 0;
+		raw3215[line] = NULL;
 		spin_unlock(&raw3215_device_lock);
 		kfree(raw);
 		return -ENOMEM;