net-next: mediatek: add fixed-phy support

The MT7623 SoC has a builtin gigabit switch. If we want to use it, GMAC1
needs to be configured using a fixed link speed and flow control settings.
The easiest way to do this is to used the fixed-phy driver, allowing us to
reuse the existing mdio polling code to setup the MAC.
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NJohn Crispin <john@phrozen.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mediatek/mtk_eth_soc.c

@@ -229,6 +229,9 @@ static int mtk_phy_connect(struct mtk_mac *mac)
 	u32 val, ge_mode;
 
 	np = of_parse_phandle(mac->of_node, "phy-handle", 0);
+	if (!np && of_phy_is_fixed_link(mac->of_node))
+		if (!of_phy_register_fixed_link(mac->of_node))
+			np = of_node_get(mac->of_node);
 	if (!np)
 		return -ENODEV;