b=17447

r=adilger,deen

- missed lustre_put_lsi() in couple of places;

- do not call deregister_mount() in mount error path, this makes it impossible for MDT to do put_mount() and thus, its lsi left not released;

- fixes error handling with llog_setup/llog_cleanup in couple of places;
- fixes error handling after hash_init errors in class_setup();
- cleanups.