vfio/ap_ops: Convert to use vfio_register_group_dev()

This is straightforward conversion, the ap_matrix_mdev is actually serving
as the vfio_device and we can replace all the mdev_get_drvdata()'s with a
simple container_of() or a dev_get_drvdata() for sysfs paths.

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Cornelia Huck <cohuck@redhat.com>
Cc: kvm@vger.kernel.org
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/0-v4-0203a4ab0596+f7-vfio_ap_jgg@nvidia.comSigned-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/s390/crypto/vfio_ap_private.h

@@ -18,6 +18,7 @@
 #include <linux/delay.h>
 #include <linux/mutex.h>
 #include <linux/kvm_host.h>
+#include <linux/vfio.h>
 
 #include "ap_bus.h"
 
@@ -79,6 +80,7 @@ struct ap_matrix {
  * @kvm:	the struct holding guest's state
  */
 struct ap_matrix_mdev {
+	struct vfio_device vdev;
 	struct list_head node;
 	struct ap_matrix matrix;
 	struct notifier_block group_notifier;