arc: fix small typos
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Reviewed-by: Rob Norris <rob.norris@klarasystems.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Shreshth Srivastava <shreshthsrivastava2@gmail.com>
Closes #17840