Coverity notes in xenapiDomainGetXMLDesc that 'vms' is dereferenced a few times before a "if (vms) xen_vm_set_free(vms);" call is made. Since we'd exit out much sooner if the fetch of the vms failed, just remove the unnecessary "if (vms)" check. (cherry picked from commit eab968c7d7b4ee94e504499dc2a4ea70643718a0)