dt-binding: ptp: Add SoC compatibility strings for dte ptp clock

dt-binding: ptp: Add SoC compatibility strings for dte ptp clock

Add SoC specific compatibility strings to the Broadcom DTE
based PTP clock binding document.

Fixed the document heading and node name.

Fixes: 80d6076140b2 ("dt-binding: ptp: add bindings document for dte based ptp clock")
Signed-off-by: Arun Parameswaran <[email protected]>
Acked-by: Rob Herring <[email protected]>
Signed-off-by: David S. Miller <[email protected]>