Free the flow metadata post a flush

Flow metadata, which is passed to the hold queue flusher, is not freed
post the flush.

Change-Id: I7764f39167403532fe01caa2b1285a183420893b
Closes-Bug: #1436798

dp-core/vr_flow.c

@@ -878,11 +878,11 @@ vr_flow_flush(void *arg)
 
     router = flmd->flmd_router;
     if (!router)
-        return;
+        goto exit_flush;
 
     fe = vr_get_flow_entry(router, flmd->flmd_index);
     if (!fe)
-        return;
+        goto exit_flush;
 
     vr_init_forwarding_md(&fmd);
     vr_flow_set_forwarding_md(router, fe, flmd->flmd_index, &fmd);
@@ -893,6 +893,9 @@ vr_flow_flush(void *arg)
         vr_reset_flow_entry(router, fe, flmd->flmd_index);
     } 
 
+exit_flush:
+    vr_free(flmd);
+
     return;
 }