s390/pci: fix struct definition for set PCI function

Recent firmware will store PCI MIO information also when enabling MIO
instructions via set PCI function. We do not use this information but
currently calling enable MIO will fail because of insufficient response
block length. Fix this by putting a struct mio_info at the end of the
affected response block struct.

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>