phy: ti: gmii-sel: do not fail in case of gmii

The "gmii" PHY interface mode is supported on TI AM335x/437x/5xx SoCs, so
don't fail if it's selected.
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

drivers/phy/ti/phy-gmii-sel.c

@@ -80,6 +80,7 @@ static int phy_gmii_sel_mode(struct phy *phy, enum phy_mode mode, int submode)
 		break;
 
 	case PHY_INTERFACE_MODE_MII:
+	case PHY_INTERFACE_MODE_GMII:
 		gmii_sel_mode = AM33XX_GMII_SEL_MODE_MII;
 		break;