Enhance ioctl number checks

When checking ZFS_IOC_* numbers, print which numbers are wrong rather
than silently failing.

Reviewed-by: Chris Dunlop <chris@onthe.net.au>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@ixsystems.com>
Closes #9187