net: fec: ptp: Use hardware algorithm to adjust PTP counter.

net: fec: ptp: Use hardware algorithm to adjust PTP counter.

The FEC IP supports hardware adjustment for ptp timer. Refer to the description of
ENET_ATCOR and ENET_ATINC registers in the spec about the hardware adjustment. This
patch uses hardware support to adjust the ptp offset and frequency on the slave side.

Signed-off-by: Luwei Zhou <[email protected]>
Signed-off-by: Frank Li <[email protected]>
Signed-off-by: Fugang Duan <[email protected]>
Signed-off-by: David S. Miller <[email protected]>