idr_destroy() can destroy idr by itself and idr_remove_all() is being
deprecated.  Drop its usage.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>