fsm: id: properly set name in case of NULL id

Since alloc relies on osmo_fsm_inst_update_id() to set the name, never skip
that.

In osmo_fsm_inst_alloc(), we allow passing a NULL id, and in
osmo_fsm_inst_update_id(), we set the name without id if id is NULL.

Change-Id: I6d6b09a811b82770818f19b189a57d9fc4a8133b
diff --git a/src/fsm.c b/src/fsm.c
index 88de011..9bbf870 100644
--- a/src/fsm.c
+++ b/src/fsm.c
@@ -263,11 +263,9 @@
 	fi->log_level = log_level;
 	osmo_timer_setup(&fi->timer, fsm_tmr_cb, fi);
 
-	if (id) {
-		if (osmo_fsm_inst_update_id(fi, id) < 0) {
-				talloc_free(fi);
-				return NULL;
-		}
+	if (osmo_fsm_inst_update_id(fi, id) < 0) {
+			talloc_free(fi);
+			return NULL;
 	}
 
 	INIT_LLIST_HEAD(&fi->proc.children);