Orphan inodes are deleted inodes which will disappear after FS
re-mount. There is not need to write orphan inodes back, because
they are not needed on the flash media.

So optimize orphans a little by not writing them back. Just mark
them as clean, free the budget, and report success to VFS.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>