[S390] smsgiucv: declare char pointers as "const"

Declare the smsgiucv prefix char pointer as "const" and use
use const char pointers in callback functions.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/net/smsgiucv.c b/drivers/s390/net/smsgiucv.c
index 67f2485..3e666b6 100644
--- a/drivers/s390/net/smsgiucv.c
+++ b/drivers/s390/net/smsgiucv.c
@@ -31,9 +31,9 @@
 
 struct smsg_callback {
 	struct list_head list;
-	char *prefix;
+	const char *prefix;
 	int len;
-	void (*callback)(char *from, char *str);
+	void (*callback)(const char *from, char *str);
 };
 
 MODULE_AUTHOR
@@ -100,8 +100,8 @@
 	kfree(buffer);
 }
 
-int smsg_register_callback(char *prefix,
-			   void (*callback)(char *from, char *str))
+int smsg_register_callback(const char *prefix,
+			   void (*callback)(const char *from, char *str))
 {
 	struct smsg_callback *cb;
 
@@ -117,8 +117,9 @@
 	return 0;
 }
 
-void smsg_unregister_callback(char *prefix,
-			      void (*callback)(char *from, char *str))
+void smsg_unregister_callback(const char *prefix,
+			      void (*callback)(const char *from,
+					       char *str))
 {
 	struct smsg_callback *cb, *tmp;