chrony: Fix privdrop packageconfig

To drop root privileges on Linux-based systems, chrony requires a
standard user to switch to and the use of capabilities. Fix up the
privdrop packageconfig to account for this.

Signed-off-by: Easwar Hariharan <easwar.hariharan@microsoft.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>