driver core: remove subsystem_init()

There is only one user of it, and it is only a wrapper for kset_init().

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Documentation/kobject.txt

@@ -238,7 +238,6 @@ kobj_set_kset_s(obj,subsys)
 - Assumes that obj->kobj exists, and is a struct kobject.
 - Sets the kset of that kobject to the kset <subsys>.
 
-void subsystem_init(struct kset *s);
 int subsystem_register(struct kset *s);
 void subsystem_unregister(struct kset *s);