Revert "privsep: default to using _dhcpcd and not _dhcp"
Revert "privsep: default to using _dhcpcd and not _dhcp"

This reverts commit 36c47a8df0951236a7842bbf8241e2932357ef61.

rsmarples/dhcpcd,rsmarples/dhcpcd,rsmarples/dhcpcd