KVM: s390: pci: add basic kvm_zdev structure

This structure will be used to carry kvm passthrough information related to
zPCI devices.

Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20220606203325.110625-12-mjrosato@linux.ibm.com


Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>