ext2: change reusable parameter to true when calling mb_cache_entry_create()

Reusable parameter of mb_cache_entry_create() is bool type,
so it's better to set true instead of 1.

Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Signed-off-by: Jan Kara <jack@suse.cz>