src: use osmo_timer_setup()

Use new function available in libosmocore to set up timers. Compile
tested only.

Change-Id: Ibcfd915688e97d370a888888a83a7c95cbe16819
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat_ctrl.c b/openbsc/src/osmo-bsc_nat/bsc_nat_ctrl.c
index 057a583..3453758 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat_ctrl.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat_ctrl.c
@@ -279,8 +279,8 @@
 			pending->cmd = cmd;
 
 			/* Setup the timeout */
-			pending->timeout.data = pending;
-			pending->timeout.cb = pending_timeout_cb;
+			osmo_timer_setup(&pending->timeout, pending_timeout_cb,
+					 pending);
 			/* TODO: Make timeout configurable */
 			osmo_timer_schedule(&pending->timeout, 10, 0);
 			llist_add_tail(&pending->list_entry, &bsc->cmd_pending);