Small Refactors

Rename TOP_DIR to THIS_DIR, change the order of variable definitions.

Change-Id: I96c12c5102e658ec76ab5176c3207fb641dae078
diff --git a/tools/xen/xenrc b/tools/xen/xenrc
index 1a5a2a9..e4d8ac9 100644
--- a/tools/xen/xenrc
+++ b/tools/xen/xenrc
@@ -32,10 +32,10 @@
 PUB_IP=${PUB_IP:-192.168.1.55}
 
 # Public network
-PUB_BR=${PUB_BR:-"xenbr0"}
-PUB_DEV=${PUB_DEV:-eth0}
-PUB_VLAN=${PUB_VLAN:--1}
 PUB_NETMASK=${PUB_NETMASK:-255.255.255.0}
+PUB_BR=${PUB_BR:-"xenbr0"}
+PUB_VLAN=${PUB_VLAN:--1}
+PUB_DEV=${PUB_DEV:-eth0}
 
 # VM network params
 VM_NETMASK=${VM_NETMASK:-255.255.255.0}