Use 3.4.8 version of OLT deb package for 2.8 release

Change-Id: Ie0106f6dd4610741936167ebdd7e99256d94e7a0
(cherry picked from commit dc8709553377244394f67775e9c16ac737b47c50)
diff --git a/deployment-configs/flex-ocp-cord-multi-uni-TT.yaml b/deployment-configs/flex-ocp-cord-multi-uni-TT.yaml
index 46b0bea..5f36625 100644
--- a/deployment-configs/flex-ocp-cord-multi-uni-TT.yaml
+++ b/deployment-configs/flex-ocp-cord-multi-uni-TT.yaml
@@ -51,7 +51,7 @@
     aggPort: '1'
     serial: 'EC1838000853'
     oltDebVersion: openolt_asfvolt16-3.4.8-eec0fc9e9a01dc0d35b0b8441e0a22a4c0cc51b4-40G-NNI.deb
-    oltDebVersion23: openolt_asfvolt16-3.3.3-1a5d68b50d8bcc5ba6cb1630d3294c30c37cd2f5-40G-NNI.deb
+    oltDebVersion23: openolt_asfvolt16-3.4.8-eec0fc9e9a01dc0d35b0b8441e0a22a4c0cc51b4-40G-NNI.deb
     board_technology: XGS-PON
 
 onus: