net: phy: vitesse: Fix cis8204 RGMII_ID code

Commit 79e86ccb3786c8b20004db3fa10a70049456f580 "vitesse: remove duplicated
argument to ||" correctly removed a redundant check.

However, I believe that the original code was simply wrong, and should have
been checking against RGMII_ID.

To fix this and avoid similar problems in the future, use the
phy_interface_is_rgmii helper function.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

drivers/net/phy/vitesse.c

@@ -127,9 +127,7 @@ static int cis8204_config(struct phy_device *phydev)
 
 	genphy_config_aneg(phydev);
 
-	if ((phydev->interface == PHY_INTERFACE_MODE_RGMII) ||
-			(phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID) ||
-			(phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID))
+	if (phy_interface_is_rgmii(phydev))
 		phy_write(phydev, MDIO_DEVAD_NONE, MIIM_CIS8204_EPHY_CON,
 				MIIM_CIS8204_EPHYCON_INIT |
 				MIIM_CIS8204_EPHYCON_RGMII);