The PCI MMIO might be disabled or the device in the reset state.
Make sure we do not dump these memory regions.

Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>