[signal] Differentiate paging success from expiration in SS_PAGING

This is useful information to know and actually fixes a segfault
in rllp.c where lchan is accessed even tough it could be NULL in
case of failure.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/openbsc/src/paging.c b/openbsc/src/paging.c
index b5dc2d0..91de702 100644
--- a/openbsc/src/paging.c
+++ b/openbsc/src/paging.c
@@ -214,7 +214,7 @@
 
 	counter_inc(req->bts->network->stats.paging.expired);
 
-	dispatch_signal(SS_PAGING, S_PAGING_COMPLETED, &sig_data);
+	dispatch_signal(SS_PAGING, S_PAGING_EXPIRED, &sig_data);
 	if (cbfn)
 		cbfn(GSM_HOOK_RR_PAGING, GSM_PAGING_EXPIRED, NULL, NULL,
 			  cbfn_param);