Add a new statistics field to track packet sent to invalid interface, which has been torn down.

Change-Id: I28a6f9b213476e149d7a2a97588071a255c4cf93
Signed-off-by: Guojun Jin <g.jin@codeaurora.org>
diff --git a/nss_n2h.c b/nss_n2h.c
index 4c0e507..d2f49f1 100755
--- a/nss_n2h.c
+++ b/nss_n2h.c
@@ -105,6 +105,8 @@
 	 */
 	nss_ctx->stats_n2h[NSS_STATS_N2H_N2H_TOT_PAYLOADS] = nnss->tot_payloads;
 
+	nss_ctx->stats_n2h[NSS_STATS_N2H_N2H_INTERFACE_INVALID] += nnss->data_interface_invalid;
+
 	spin_unlock_bh(&nss_top->stats_lock);
 }