Disable vnc on Power Systems

Power systems don't have graphics adapters, so we can't simulate a VNC
console. This patch removes that from the default nova configuration
if the system architecture is ppc64.

Change-Id: I129d180b712115e5c275241740d34805fea23e8b
diff --git a/stack.sh b/stack.sh
index 4089531..f8d546f 100755
--- a/stack.sh
+++ b/stack.sh
@@ -1108,6 +1108,10 @@
         iniset $NOVA_CONF DEFAULT compute_driver "libvirt.LibvirtDriver"
         LIBVIRT_FIREWALL_DRIVER=${LIBVIRT_FIREWALL_DRIVER:-"nova.virt.libvirt.firewall.IptablesFirewallDriver"}
         iniset $NOVA_CONF DEFAULT firewall_driver "$LIBVIRT_FIREWALL_DRIVER"
+        # Power architecture currently does not support graphical consoles.
+        if is_arch "ppc64"; then
+            iniset $NOVA_CONF DEFAULT vnc_enabled "false"
+        fi
     fi
 
     init_nova_cells