[S390] tape: cleanup reference counting

Rename tape_get_device to tape_find_device and tape_get_device_reference
to tape_get_device. The old names didn't make too much sense.

Follow the get_device()/put_device() semantic and convert tape_put_device
to a void function.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/char/tape_34xx.c b/drivers/s390/char/tape_34xx.c
index 2fe45ff..3657fe1 100644
--- a/drivers/s390/char/tape_34xx.c
+++ b/drivers/s390/char/tape_34xx.c
@@ -113,16 +113,16 @@
 {
 	struct tape_34xx_work *p =
 		container_of(work, struct tape_34xx_work, work);
+	struct tape_device *device = p->device;
 
 	switch(p->op) {
 		case TO_MSEN:
-			tape_34xx_medium_sense(p->device);
+			tape_34xx_medium_sense(device);
 			break;
 		default:
 			DBF_EVENT(3, "T34XX: internal error: unknown work\n");
 	}
-
-	p->device = tape_put_device(p->device);
+	tape_put_device(device);
 	kfree(p);
 }
 
@@ -136,7 +136,7 @@
 
 	INIT_WORK(&p->work, tape_34xx_work_handler);
 
-	p->device = tape_get_device_reference(device);
+	p->device = tape_get_device(device);
 	p->op     = op;
 
 	schedule_work(&p->work);