drivers: net: cpsw: Enable CPTS for DRA7xx and AM4372

Enable cpts hardware time stamping for Dra7xx and AM4372.
This enables PTPv2 for DRA7xx and AM4372.

Signed-off-by: George Cherian <george.cherian@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>