net: phy: microchip_rds_ptp: Add header file for Microchip rds ptp library

This rds ptp header file will cover ptp macros for future phys in
Microchip where addresses will be same but base offset and mmd address
may changes.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Signed-off-by: Divya Koppera <divya.koppera@microchip.com>
Link: https://patch.msgid.link/20241219123311.30213-2-divya.koppera@microchip.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>