VOL-4268: Migrate to BAL3.4.9.9 for voltha-2.8 release

Change-Id: I4ad88e7aae992856b1b127902cff6e19a05e4314
diff --git a/deployment-configs/flex-ocp-cord-multi-uni-TT.yaml b/deployment-configs/flex-ocp-cord-multi-uni-TT.yaml
index ada550b..6433ae9 100644
--- a/deployment-configs/flex-ocp-cord-multi-uni-TT.yaml
+++ b/deployment-configs/flex-ocp-cord-multi-uni-TT.yaml
@@ -50,7 +50,7 @@
     fortygig: 'true'
     aggPort: '1'
     serial: 'EC1838000853'
-    oltDebVersion: openolt_asfvolt16-3.4.8-eec0fc9e9a01dc0d35b0b8441e0a22a4c0cc51b4-40G-NNI.deb
+    oltDebVersion: openolt_asfvolt16-3.4.9-e2a9597f3d690fe3a0ea0df244571dfc9e8c2833-40G-NNI.deb
     board_technology: XGS-PON
 
 onus: