s390: cio: remove redundant cio_cancel declaration

cio_cancel was declared twice. Remove one of them.
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/cio/cio.h

@@ -127,7 +127,6 @@ extern int cio_resume (struct subchannel *);
 extern int cio_halt (struct subchannel *);
 extern int cio_start (struct subchannel *, struct ccw1 *, __u8);
 extern int cio_start_key (struct subchannel *, struct ccw1 *, __u8, __u8);
-extern int cio_cancel (struct subchannel *);
 extern int cio_set_options (struct subchannel *, int);
 extern int cio_update_schib(struct subchannel *sch);
 extern int cio_commit_config(struct subchannel *sch);