ptp: Add clock driver for the OpenCompute TimeCard.

The OpenCompute time card is an atomic clock along with
a GPS receiver that provides a Grandmaster clock source
for a PTP enabled network.

More information is available at http://www.timingcard.com/



Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Link: https://lore.kernel.org/r/20201204035128.2219252-2-jonathan.lemon@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>