PSGMII is a Qualcomm specific mode similar to QSGMII but it has 5 SGMII
lines instead of 4 in QSGMII.
This just adds the support for the PHY layer to be able to identify the
mode for further use.
It is required for the DSA driver.
Signed-off-by: Robert Marko <robert.marko@sartura.hr>
