handover_logic: set correct link to bts for subscriber_connection in case of moving this connection to another bts

In case of successful completion of handover gsm_subscriber_connection could be moved from one bts to another,
so connection link to bts should be replaced by link to bts, which owns new_lchan.
This bug was detected, because conn->bts->nr is used in call control log messages
and wrong number of bts was observed in these messages after handover.

Change-Id: Idc7dd412b7580c451e716b73ef7549826c60b0d9
diff --git a/src/libbsc/handover_logic.c b/src/libbsc/handover_logic.c
index c03563f..57d1dcd 100644
--- a/src/libbsc/handover_logic.c
+++ b/src/libbsc/handover_logic.c
@@ -282,6 +282,7 @@
 
 	new_lchan->conn->ho_lchan = NULL;
 	new_lchan->conn->lchan = new_lchan;
+	new_lchan->conn->bts = new_lchan->ts->trx->bts;
 	ho->old_lchan->conn = NULL;
 
 	lchan_release(ho->old_lchan, 0, RSL_REL_LOCAL_END);