net: ethernet: mediatek: mark symbols static where possible

We get 2 warnings when building kernel with W=1:
drivers/net/ethernet/mediatek/mtk_eth_soc.c:2041:5: warning: no previous prototype for 'mtk_get_link_ksettings' [-Wmissing-prototypes]
drivers/net/ethernet/mediatek/mtk_eth_soc.c:2052:5: warning: no previous prototype for 'mtk_set_link_ksettings' [-Wmissing-prototypes]

In fact, these functions are only used in the file in which they are
declared and don't need a declaration, but can be made static.
So this patch marks these functions with 'static'.
Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mediatek/mtk_eth_soc.c

@@ -2038,7 +2038,7 @@ static int mtk_cleanup(struct mtk_eth *eth)
 	return 0;
 }
 
-int mtk_get_link_ksettings(struct net_device *ndev,
+static int mtk_get_link_ksettings(struct net_device *ndev,
 				  struct ethtool_link_ksettings *cmd)
 {
 	struct mtk_mac *mac = netdev_priv(ndev);
@@ -2049,7 +2049,7 @@ int mtk_get_link_ksettings(struct net_device *ndev,
 	return phy_ethtool_ksettings_get(ndev->phydev, cmd);
 }
 
-int mtk_set_link_ksettings(struct net_device *ndev,
+static int mtk_set_link_ksettings(struct net_device *ndev,
 				  const struct ethtool_link_ksettings *cmd)
 {
 	struct mtk_mac *mac = netdev_priv(ndev);