Fixes an issue with flow deletion.

Don't look for uni port number in metadata in match. This only
has C-vlan info now, and only for downstream flows.

Change-Id: I90141048ca4082e2ead7a00f907b53639152b4a3
(cherry picked from commit dd27fbb9d32da143ede7bc48435b4d72fde83b79)
diff --git a/voltha/adapters/openolt/openolt_platform.py b/voltha/adapters/openolt/openolt_platform.py
index dd26b39..a56b319 100644
--- a/voltha/adapters/openolt/openolt_platform.py
+++ b/voltha/adapters/openolt/openolt_platform.py
@@ -160,11 +160,6 @@
                     uni_port_no = field.port
                     break
         elif flow_direction == "downstream":
-            for field in fd.get_ofb_fields(flow):
-                if field.type == fd.METADATA:
-                    uni_port_no = field.table_metadata & 0xFFFFFFFF
-                    break
-
             if uni_port_no is None:
                 for action in fd.get_actions(flow):
                     if action.type == fd.OUTPUT: