markers/tracpoints: fix non-modular build

fix:

 kernel/marker.c: In function 'marker_module_notify':
 kernel/marker.c:905: error: 'MODULE_STATE_COMING' undeclared (first use in this function)
 [...]

Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/marker.c b/kernel/marker.c
index c14ec26..ea54f26 100644
--- a/kernel/marker.c
+++ b/kernel/marker.c
@@ -896,6 +896,8 @@
 }
 EXPORT_SYMBOL_GPL(marker_get_private_data);
 
+#ifdef CONFIG_MODULES
+
 int marker_module_notify(struct notifier_block *self,
 			 unsigned long val, void *data)
 {
@@ -924,3 +926,5 @@
 	return register_module_notifier(&marker_module_nb);
 }
 __initcall(init_markers);
+
+#endif /* CONFIG_MODULES */