Update tost-onos to match the latest updates

Change-Id: I5f371e612f088dca3743ab439841e8899c5b2f57
diff --git a/Makefile.vars.master b/Makefile.vars.master
index e79841a..58ab187 100644
--- a/Makefile.vars.master
+++ b/Makefile.vars.master
@@ -26,7 +26,7 @@
 # (2) Checkout Local source code (local branch not yet pushed);
 # (3) Fetch from Gerrit/Github (pending review in the form of refs/changes/... or pending pull request);
 
-export ONOS_VERSION            ?= master
+export ONOS_VERSION            ?= onos-2.5
 export TRELLIS_CONTROL_VERSION ?= 3.0.1-SNAPSHOT
 export TRELLIS_T3_VERSION      ?= 4.0.0-SNAPSHOT
 export FABRIC_TOFINO_VERSION   ?= master