VOL-1261: Fix ONU Response Time field size in ANI-G ME

Change-Id: Ia1ce3666c98774853e92aa959958a7938c375cc3
diff --git a/voltha/extensions/omci/omci_entities.py b/voltha/extensions/omci/omci_entities.py
index e7bc9b8..ea0e856 100644
--- a/voltha/extensions/omci/omci_entities.py
+++ b/voltha/extensions/omci/omci_entities.py
@@ -715,7 +715,7 @@
         ECA(ShortField("optical_signal_level", None), {AA.R}),
         ECA(ByteField("lower_optical_threshold", 0xFF), {AA.R, AA.W}),
         ECA(ByteField("upper_optical_threshold", 0xFF), {AA.R, AA.W}),
-        ECA(ByteField("ont_response_time", None), {AA.R}),
+        ECA(ShortField("ont_response_time", None), {AA.R}),
         ECA(ShortField("transmit_optical_level", None), {AA.R}),
         ECA(ByteField("lower_transmit_power_threshold", 0x81), {AA.R, AA.W}),
         ECA(ByteField("upper_transmit_power_threshold", 0x81), {AA.R, AA.W}),