KVM: s390: add bitmap for handling cpu-local interrupts

Adds a bitmap to the vcpu structure which is used to keep track
of local pending interrupts. Also add enum with all interrupt
types sorted in order of priority (highest to lowest)

Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>