schema: fix some problems in network/interface schemas

<portgroup> allows a <bandwidth> element, but the schema didn't have
this. Since this makes for multiple elements in portgroup, they must
be interleaved.

<interface type='bridge'> needs to allow <virtualport> elements
for openvswitch, but the schema didn't allow this.

docs/schemas/domaincommon.rng

@@ -1410,6 +1410,9 @@
                 <empty/>
               </element>
             </optional>
+            <optional>
+              <ref name="virtualPortProfile"/>
+            </optional>
             <ref name="interface-options"/>
           </interleave>
         </group>

docs/schemas/network.rng

@@ -133,9 +133,14 @@
                 </choice>
               </attribute>
             </optional>
-            <optional>
-              <ref name="virtualPortProfile"/>
-            </optional>
+            <interleave>
+              <optional>
+                <ref name="virtualPortProfile"/>
+              </optional>
+              <optional>
+                <ref name="bandwidth"/>
+              </optional>
+            </interleave>
           </element>
         </zeroOrMore>