net: mscc: PTP Hardware Clock (PHC) support

This patch adds support for PTP Hardware Clock (PHC) to the Ocelot
switch for both PTP 1-step and 2-step modes.

Signed-off-by: Antoine Tenart <[email protected]>
Acked-by: Richard Cochran <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: atenart