disabled dns on bridged interfaces

As we have no dnsmasq installed, disabling dns should suppress errors during libvirt startup

install_kvm.sh

@@ -17,6 +17,7 @@ cat >/tmp/host-bridge.xml <<EOL
   <name>host-bridge</name>
   <forward mode="bridge"/>
   <bridge name="br0"/>
+  <dns enable="no"/>
 </network>
 EOL
 virsh net-define /tmp/host-bridge.xml
@@ -27,11 +28,12 @@ rm /tmp/host-bridge.xml
 
 # Create isolated network (without DHCP)
 cat >/tmp/isolated-bridge.xml <<EOL
-    <network>
-      <name>isolated-bridge</name>
-      <forward mode="bridge"/>
-      <bridge name="br1"/>
-    </network>
+<network>
+  <name>isolated-bridge</name>
+  <forward mode="bridge"/>
+  <bridge name="br1"/>
+   <dns enable="no"/>
+</network>
 EOL
 virsh net-define /tmp/isolated-bridge.xml
 virsh net-autostart isolated-bridge