net: dsa: mt7530: 1G can also support 1000BASE-X link mode

When using an external PHY connected using RGMII to mt7531 port 5, the
PHY can be used to used support 1000BASE-X connections. Moreover, if
1000BASE-T is supported, then we should allow 1000BASE-X as well, since
which are supported is a property of the PHY.

Therefore, it makes no sense to exclude this from the linkmodes when
1000BASE-T is supported.

Fixes: c288575f78 ("net: dsa: mt7530: Add the support of MT7531 switch")
Tested-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/dsa/mt7530.c

@@ -2539,13 +2539,7 @@ static void mt7531_sgmii_validate(struct mt7530_priv *priv, int port,
 	/* Port5 supports ethier RGMII or SGMII.
 	 * Port6 supports SGMII only.
 	 */
-	switch (port) {
-	case 5:
-		if (mt7531_is_rgmii_port(priv, port))
-			break;
-		fallthrough;
-	case 6:
-		phylink_set(supported, 1000baseX_Full);
+	if (port == 6) {
 		phylink_set(supported, 2500baseX_Full);
 		phylink_set(supported, 2500baseT_Full);
 	}
@@ -2913,8 +2907,6 @@ static void
 mt7530_mac_port_validate(struct dsa_switch *ds, int port,
 			 unsigned long *supported)
 {
-	if (port == 5)
-		phylink_set(supported, 1000baseX_Full);
 }
 
 static void mt7531_mac_port_validate(struct dsa_switch *ds, int port,
@@ -2951,8 +2943,10 @@ mt753x_phylink_validate(struct dsa_switch *ds, int port,
 	}
 
 	/* This switch only supports 1G full-duplex. */
-	if (state->interface != PHY_INTERFACE_MODE_MII)
+	if (state->interface != PHY_INTERFACE_MODE_MII) {
 		phylink_set(mask, 1000baseT_Full);
+		phylink_set(mask, 1000baseX_Full);
+	}
 
 	priv->info->mac_port_validate(ds, port, mask);