spa_preferred_class: pass the entire zio

Rather than picking out specific values out of the properties, just pass
the entire zio in, to make it easier in the future to use more of that
info to decide on the storage class.

I would have rathered just pass io_prop in, but having spa.h include
zio.h gets a bit tricky.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Sponsored-by: Klara, Inc.
Sponsored-by: iXsystems, Inc.
Closes #15894