Add rkcomphy(3), a driver for the "naneng" combo PHY found on the RK356x

Add rkcomphy(3), a driver for the "naneng" combo PHY found on the RK356x
(and RK3588).  This is a PIPE PHY with support for PCIe, SATA, USB3, SGMII
and QSGMII.  For now only PCIe, SATA and USB3 support are implemented.
SATA support has not been tested.

Also add the refernce clocks needed by the PHYs to rkclock(4).

ok mlarkin@