KVM: Provide function for VCPU lookup by id
KVM: Provide function for VCPU lookup by id

Let's provide a function to lookup a VCPU by id.

Reviewed-by: Christian Borntraeger <49712f635b03c16d7f4c43df70e49ec8c565813d@de.ibm.com>
Reviewed-by: Dominik Dingel <d1e5197fc3340c52389f7f33900df40c6bf98e12@linux.vnet.ibm.com>
Signed-off-by: David Hildenbrand <ae115cfa58aaa81618f054056f573d0d78c5ed09@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <49712f635b03c16d7f4c43df70e49ec8c565813d@de.ibm.com>
[split patch from refactoring patch]

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs