Add PTP Support

[ainguraXmarquiegui]

cn9130-som specifications state that CN9130-SOM should have 1588 support, but looking at ethtool it seems that eth1 and eth2 on CN9130-CF-BASE doesn't still support hardware timestamping.

It would be great to have hardware timestamping support in Linux.

[ainguraXmarquiegui]

@Josua-SR , I have just discovered this commit: 2969fe9

What's the status of PTP for the CN9130? Is hardware timestamping working properly with a specific kernel version?

[Josua-SR]

Based on mvpp2 driver change history in the kernel, PTP can be enabled on CN9130 integrated network interfaces.
However SolidRun have tested neither the basic functionality nor adherence to PTP spec. Based on Marvell documentation that is available under NDA there may be known issues with the PTP hardware in CN9130 SoC.