Remove inappropiate error message suggesting to use '-r'

Removes an incorrect error message from libzfs that suggests applying
'-r' when a zfs subcommand is called with a filesystem path while
expecting either a snapshot or bookmark path.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Kjeld Schouten <kjeld@schouten-lebbing.nl>
Signed-off-by: InsanePrawn <insane.prawny@gmail.com>
Closes #9574