Support Precision Time Protocol (PTP)

[zephyrbot]

Reported by Anas Nashif:

L2 protocol enabling clock synchronisation over the network with higher precision and low overhead. Precision can be nanosecond or microsecond range.
PTP provides precise time coordination of Ethernet LAN connected computers. It was designed primarily for instrumentation and control systems.

(Imported from Jira ZEP-1606)

[nashif]

this is completed.