[paging] Do not use request after it was was destroyed..

Increment the counter before we call the remove request
which is freeing the request...
diff --git a/openbsc/src/paging.c b/openbsc/src/paging.c
index 9c978be..3d16a21 100644
--- a/openbsc/src/paging.c
+++ b/openbsc/src/paging.c
@@ -208,11 +208,11 @@
 	sig_data.lchan	= NULL;
 
 	/* must be destroyed before calling cbfn, to prevent double free */
+	counter_inc(req->bts->network->stats.paging.expired);
 	cbfn_param = req->cbfn_param;
 	cbfn = req->cbfn;
 	paging_remove_request(&req->bts->paging, req);
 
-	counter_inc(req->bts->network->stats.paging.expired);
 
 	dispatch_signal(SS_PAGING, S_PAGING_EXPIRED, &sig_data);
 	if (cbfn)