s390x: always provide pci support

s390x: always provide pci support

We tried to make pci support optional on s390x in the past;
unfortunately, we still require the s390 phb to be created
unconditionally due to backwards compatibility issues.

Instead of sinking more effort into this (including compat
handling for older machines etc.) for non-obvious gains, let's
just make CONFIG_PCI something that is always set on s390x.

Note that you can still fence off pci for the _guest_ if you
provide a cpu model without the zpci feature.

Message-Id: <20190211113255.3837-1-cohuck@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>