gprs_ns2: calculate the nse->*_sums before notifing the sns fsm

The sns fsm needs these information to determine if there is a signalling nsvc left

Change-Id: I7b115921780bd1ae895d8b9d0d4aec3e1cbaaf58
diff --git a/src/gb/gprs_ns2.c b/src/gb/gprs_ns2.c
index adf3b32..6c48ca6 100644
--- a/src/gb/gprs_ns2.c
+++ b/src/gb/gprs_ns2.c
@@ -1391,8 +1391,8 @@
 {
 	struct gprs_ns2_nse *nse = nsvc->nse;
 
-	ns2_sns_notify_alive(nse, nsvc, unblocked);
 	ns2_nse_data_sum(nse);
+	ns2_sns_notify_alive(nse, nsvc, unblocked);
 
 	if (unblocked == nse->alive)
 		return;