sysutils/py-salt: revert upstream PR 55719

Salt PR 55719 changed the signature of Linux's sysctl.persist function,
without changing it for any other OS. Widespread breakage is the result.
Revert that PR until upstream fixes it.

PR: 247627
Reported by: ari@ish.com.au
Approved by: 0mp (ports)
Approved by: christer.edwards@gmail.com (maintainer timeout)
MFH: 2020Q3
Sponsored by: Axcient