KVM: s390: introduce struct kvm_s390_gisa_interrupt

Use this struct analog to the kvm interruption structs
for kvm emulated floating and local interruptions.

GIB handling will add further fields to this structure as
required.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Message-Id: <20190131085247.13826-8-mimu@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>