smpp_smsc.c: Log on sending deliver_sm message

Change-Id: Ie16294df6d5bc0065f8d2b49320ead61f535f271
diff --git a/src/libmsc/smpp_smsc.c b/src/libmsc/smpp_smsc.c
index 48a1192..4c2e4aa 100644
--- a/src/libmsc/smpp_smsc.c
+++ b/src/libmsc/smpp_smsc.c
@@ -654,6 +654,9 @@
 {
 	deliver->sequence_number = esme_inc_seq_nr(esme);
 
+	LOGP(DSMPP, LOGL_DEBUG, "[%s] Tx DELIVER-SM (from %s)\n",
+		esme->system_id, deliver->source_addr);
+
 	return PACK_AND_SEND(esme, deliver);
 }