Introduce type constant. Introduce cast macro and drop dummy busdev
field used with FROM_SYSBUS() that would've broken SYS_BUS_DEVICE().
Avoid accessing parent fields directly.
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>