ptp_pch: use mac_pton()

Use mac_pton() instead of custom approach.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Link: https://lore.kernel.org/r/20220207210730.75252-1-andriy.shevchenko@linux.intel.com


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