ptp: pch: convert to the 64 bit get/set time methods.

The device has a 64 bit clock register, where each clock tick is 32
nanoseconds, and so with this patch the driver is ready for the year
2038.

Compile tested only.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>