net: phy: Makefile: Add makefile support for rds ptp in Microchip phys

Add makefile support for rds ptp library.

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/20241219123311.30213-5-divya.koppera@microchip.com


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