conf: Combine if condition in virDomainObjUpdateModificationImpact

Prior to commit id '3d021381' virDomainObjUpdateModificationImpact was
part of virDomainLiveConfigHelperMethod and the *flags if condition
VIR_DOMAIN_AFFECT_CONFIG checked the ->persistent boolean and made the
virDomainObjGetPersistentDef call.

Since the functions were split the ->persistent check is all that remained
and thus could be combined into one if statement.
Signed-off-by: NNikolay Shirokovskiy <nshirokovskiy@virtuozzo.com>
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/conf/domain_conf.c

@@ -2879,13 +2879,11 @@ virDomainObjUpdateModificationImpact(virDomainObjPtr vm,
         return -1;
     }
 
-    if (*flags & VIR_DOMAIN_AFFECT_CONFIG) {
-        if (!vm->persistent) {
-            virReportError(VIR_ERR_OPERATION_INVALID, "%s",
-                           _("transient domains do not have any "
-                             "persistent config"));
-            return -1;
-        }
+    if (!vm->persistent && (*flags & VIR_DOMAIN_AFFECT_CONFIG)) {
+        virReportError(VIR_ERR_OPERATION_INVALID, "%s",
+                       _("transient domains do not have any "
+                         "persistent config"));
+        return -1;
     }
 
     return 0;