Commit 7f60329 removed several kstats which arc_summary.py read.
Remove these kstats from arc_summary.py in the same way this was
handled in FreeNAS.
FreeNAS-commit: https://github.com/freenas/freenas/commit/3901f73
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#4695