simplify the mdev interface v2

[Christoph Hellwig]

Hi all,

this series signigicantly simplies the mdev driver interface by following
the patterns for device model interaction used elsewhere in the kernel.

Changes since v1:
 - embedd the mdev_parent into a different sub-structure in i916
 - remove headers now inclued by mdev.h from individual source files
 - pass an array of mdev_types to mdev_register_parent
 - add additional patches to implement all attributes on the
   mdev_type in the core code

Diffstat:
 Documentation/driver-api/vfio-mediated-device.rst |   26 +-
 Documentation/s390/vfio-ap.rst                    |    2 
 Documentation/s390/vfio-ccw.rst                   |    2 
 drivers/gpu/drm/i915/gvt/gvt.h                    |    6 
 drivers/gpu/drm/i915/gvt/kvmgt.c                  |  158 +++------------
 drivers/gpu/drm/i915/gvt/vgpu.c                   |   60 +----
 drivers/s390/cio/cio.h                            |    4 
 drivers/s390/cio/vfio_ccw_drv.c                   |    3 
 drivers/s390/cio/vfio_ccw_ops.c                   |   60 -----
 drivers/s390/cio/vfio_ccw_private.h               |    2 
 drivers/s390/crypto/vfio_ap_ops.c                 |   68 ------
 drivers/s390/crypto/vfio_ap_private.h             |    6 
 drivers/vfio/mdev/mdev_core.c                     |  214 ++++++--------------
 drivers/vfio/mdev/mdev_driver.c                   |    7 
 drivers/vfio/mdev/mdev_private.h                  |   39 ---
 drivers/vfio/mdev/mdev_sysfs.c                    |  230 ++++++++--------------
 include/linux/mdev.h                              |   77 +++----
 samples/vfio-mdev/mbochs.c                        |  103 ++-------
 samples/vfio-mdev/mdpy.c                          |  115 ++---------
 samples/vfio-mdev/mtty.c                          |   94 +++-----
 20 files changed, 389 insertions(+), 887 deletions(-)