Make cdev infrastructure initialize early

Very early initialization (core_initcall) needs to have the cdev
initialization done.  So make it part of the pre-initcall sequence, the
same way the bdev caches were done.

fs/char_dev.c

@@ -457,11 +457,9 @@ static struct kobject *base_probe(dev_t dev, int *part, void *data)
 	return NULL;
 }
 
-static int __init chrdev_init(void)
+void __init chrdev_init(void)
 {
 	subsystem_register(&cdev_subsys);
 	kset_register(&kset_dynamic);
 	cdev_map = kobj_map_init(base_probe, &cdev_subsys);
-	return 0;
 }
-subsys_initcall(chrdev_init);

fs/dcache.c

@@ -1606,6 +1606,7 @@ kmem_cache_t *filp_cachep;
 EXPORT_SYMBOL(d_genocide);
 
 extern void bdev_cache_init(void);
+extern void chrdev_init(void);
 
 void __init vfs_caches_init(unsigned long mempages)
 {
@@ -1626,4 +1627,5 @@ void __init vfs_caches_init(unsigned long mempages)
 	files_init(mempages); 
 	mnt_init(mempages);
 	bdev_cache_init();
+	chrdev_init();
 }