Change "secrete" to "secret"

Apparently this is intentional as a joke on devstack leaking
passwords, but the dual meaning of the word confuses people.  Let's
change it before we get yet another review fixing it.

Change-Id: I3bee03612f6ea197362aab04a37f81043f77f235
diff --git a/tools/xen/xenrc b/tools/xen/xenrc
index be6c5ca..bb27454 100644
--- a/tools/xen/xenrc
+++ b/tools/xen/xenrc
@@ -32,7 +32,7 @@
 XEN_INT_BRIDGE_OR_NET_NAME="OpenStack VM Integration Network"
 
 # VM Password
-GUEST_PASSWORD=${GUEST_PASSWORD:-secrete}
+GUEST_PASSWORD=${GUEST_PASSWORD:-secret}
 
 # Extracted variables for OpenStack VM network device numbers.
 # Make sure they form a continuous sequence starting from 0