phy: lan966x: add support for QUSGMII

Makes so that the serdes driver also takes QUSGMII in consideration.
It's configured exactly as QSGMII as far as the serdes driver is
concerned.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/phy/microchip/lan966x_serdes.c

@@ -401,6 +401,9 @@ static int serdes_set_mode(struct phy *phy, enum phy_mode mode, int submode)
 	    submode == PHY_INTERFACE_MODE_2500BASEX)
 		submode = PHY_INTERFACE_MODE_SGMII;
 
+	if (submode == PHY_INTERFACE_MODE_QUSGMII)
+		submode = PHY_INTERFACE_MODE_QSGMII;
+
 	for (i = 0; i < ARRAY_SIZE(lan966x_serdes_muxes); i++) {
 		if (macro->idx != lan966x_serdes_muxes[i].idx ||
 		    mode != lan966x_serdes_muxes[i].mode ||