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/functions b/functions
index 8aba10d..c611e00 100644
--- a/functions
+++ b/functions
@@ -471,6 +471,13 @@
     fi
 }
 
+# Utility function for checking machine architecture
+# is_arch arch-type
+function is_arch {
+    ARCH_TYPE=$1
+
+    [ "($uname -m)" = "$ARCH_TYPE" ]
+}
 
 # git clone only if directory doesn't exist already.  Since ``DEST`` might not
 # be owned by the installation user, we create the directory and change the