Drop "All rights reserved" from files by trasz@FreeBSD.org

This obeys the change in freebsd/freebsd-src@bce7ee9d4

External-issue: https://reviews.freebsd.org/D26980
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Martin Matuska <mm@FreeBSD.org>
Closes #11947