[S390] dasd: check_characteristics cleanup

Fix a broken memset (sizeof pointer vs sizeof the underlying
structure) by cleaning up the involved functions.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/block/dasd_int.h b/drivers/s390/block/dasd_int.h
index c1e487f..3ab69b5 100644
--- a/drivers/s390/block/dasd_int.h
+++ b/drivers/s390/block/dasd_int.h
@@ -578,7 +578,7 @@
 int dasd_generic_notify(struct ccw_device *, int);
 void dasd_generic_handle_state_change(struct dasd_device *);
 
-int dasd_generic_read_dev_chars(struct dasd_device *, char *, void **, int);
+int dasd_generic_read_dev_chars(struct dasd_device *, char *, void *, int);
 char *dasd_get_sense(struct irb *);
 
 /* externals in dasd_devmap.c */