s390/sclp: introduce check for the SIGP Interpretation Facility

This patch introduces the infrastructure to check whether the SIGP
Interpretation Facility is installed on all VCPUs in the configuration.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>