[S390] fix typo in vmcp.

Fix comment typo in vmcp, it is z/VM and not v/VM.

Signed-off-by: Christian Borntraeger <cborntra@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/char/vmcp.h

@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2004, 2005 IBM Corporation
- * Interface implementation for communication with the v/VM control program
+ * Interface implementation for communication with the z/VM control program
  * Version 1.0
  * Author(s): Christian Borntraeger <cborntra@de.ibm.com>
  *