vfio: Introduce capability definitions for VFIO_DEVICE_GET_INFO

Allow the VFIO_DEVICE_GET_INFO ioctl to include a capability chain.
Add a flag indicating capability chain support, and introduce the
definitions for the first set of capabilities which are specified to
s390 zPCI devices.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>