Use the saved property index instead of looking it up once per DSL
directory when traversing up towards the root.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Igor Kozhukhov <igor@dilos.org> Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu> Reviewed-by: Allan Jude <allan@klarasystems.com> Reviewed-by: Akash B <akash-b@hpe.com> Signed-off-by: Mark Johnston <markj@FreeBSD.org> Sponsored-by: The FreeBSD Foundation
Closes #14397