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

This patch changes the driver to use the newer API.

Depending on how the hardware represents a time value, this driver may
or may not yet be 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>