MAINTAINERS: additional files related kvm s390 pci passthrough

Add entries from the s390 kvm subdirectory related to pci passthrough.

Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Link: https://lore.kernel.org/r/20220606203325.110625-22-mjrosato@linux.ibm.com


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