FreeBSD: Return Mach error codes from VOP_(GET|PUT)PAGES

FreeBSD's memory management system uses its own error numbers and gets
confused when these VOPs return EIO.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reported-by: Peter Holm <pho@FreeBSD.org>
Signed-off-by: Mark Johnston <markj@FreeBSD.org>
Closes #13311