s390/pci: fix assignment of bus resources

Adjust bus resources depending on the usage of MIO instructions.

Fixes: 71ba41c9

 ("s390/pci: provide support for MIO instructions")
Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>