lan743x: lan743x: Add PTP support

PTP support includes:
    Ingress, and egress timestamping.
    One step timestamping available.
    PTP clock support.
    Periodic output support.

Signed-off-by: Bryan Whitehead <Bryan.Whitehead@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>