ONE-33 "one statistics flush" throws assert when one counter not added

Change-Id: Id10f10889c3036a6db21c999c1e6c54fc1770213
Signed-off-by: Swarup Nayak <swarupnpvt@gmail.com>
diff --git a/src/vnet/lisp-gpe/lisp_gpe_fwd_entry.c b/src/vnet/lisp-gpe/lisp_gpe_fwd_entry.c
index ca1e320..f810ae5 100644
--- a/src/vnet/lisp-gpe/lisp_gpe_fwd_entry.c
+++ b/src/vnet/lisp-gpe/lisp_gpe_fwd_entry.c
@@ -1289,6 +1289,9 @@
   vlib_combined_counter_main_t *cm = &lgm->counters;
   u32 i;
 
+  if (cm->counters == NULL)
+    return 0;
+
   for (i = 0; i < vlib_combined_counter_n_counters (cm); i++)
     vlib_zero_combined_counter (cm, i);