s390/pci: stash dtsm and maxstbl

s390/pci: stash dtsm and maxstbl

Store information about what IOAT designation types are supported by
underlying hardware as well as the largest store block size allowed.
These values will be needed by passthrough.

Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20220606203325.110625-10-mjrosato@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>