conf: Don't validate vcpu count in XML parser

Validating the vcpu count is more intricate and doing it in the XML
parser will make previously valid configs (with older qemus) vanish.

Now that we have a very similar check in the qemu domain validation
callback we can do it in a more appropriate place.

This basically reverts commit b54de0830a.

Partially resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1370066

src/conf/domain_conf.c

@@ -16376,15 +16376,6 @@ virDomainDefParseXML(xmlDocPtr xml,
 
         if (def->cpu == NULL)
             goto error;
-
-        if (def->cpu->sockets &&
-            virDomainDefGetVcpusMax(def) >
-            def->cpu->sockets * def->cpu->cores * def->cpu->threads) {
-            virReportError(VIR_ERR_XML_DETAIL, "%s",
-                           _("Maximum CPUs greater than topology limit"));
-            goto error;
-        }
-
     }
 
     if (virDomainNumaDefCPUParseXML(def->numa, ctxt) < 0)