Add Debian OS support in DevStack

Fix bug #1176216

Change-Id: Ia94c332f02a921a936db249dc3b4a7ae4eff0400
diff --git a/lib/baremetal b/lib/baremetal
index 8658c3a..bed3c09 100644
--- a/lib/baremetal
+++ b/lib/baremetal
@@ -204,7 +204,7 @@
     sudo mkdir -p /tftpboot
     sudo mkdir -p /tftpboot/pxelinux.cfg
     sudo cp /usr/lib/syslinux/pxelinux.0 /tftpboot/
-    sudo chown -R $STACK_USER:libvirtd /tftpboot
+    sudo chown -R $STACK_USER:$LIBVIRT_GROUP /tftpboot
 
     # ensure $NOVA_STATE_PATH/baremetal is prepared
     sudo mkdir -p $NOVA_STATE_PATH/baremetal