The kernel supports different PTP_SYS_OFFSET* ioctls. Use the sysoff
enum to allow selecting between them in sysoff_measure().
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
If the delay is known, print it together with the offset and frequency.
Remove the time stamp from the output to fit it into 80 chars.
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>