s390 vfio-ccw: Add bootindex property and IPLB data

s390 vfio-ccw: Add bootindex property and IPLB data

Add bootindex property and iplb data for vfio-ccw devices. This allows us to
forward boot information into the bios for vfio-ccw devices.

Refactor s390_get_ccw_device() to return device type. This prevents us from
having to use messy casting logic in several places.

Signed-off-by: Jason J. Herne <jjherne@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1554388475-18329-2-git-send-email-jjherne@linux.ibm.com>
[thuth: fixed "typedef struct VFIOCCWDevice" build failure with clang]
Signed-off-by: Thomas Huth <thuth@redhat.com>