mediatek: let mtk_eth_soc MAC announce 2500Base-T mode

To allows Ethernet phys supporting 2500Base-T mode to announce that
speed, enable the corresponding bit in mtk_eth_soc driver.
This should hopefully unlock 2500Base-T speed on the UniFi 6 LR.

Signed-off-by: Daniel Golle <[email protected]>

target/linux/mediatek/patches-5.10/703-net-ethernet-mtk_eth_soc-announce-2500baseT.patch

@@ -0,0 +1,10 @@
+--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
++++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+@@ -564,6 +564,7 @@ static void mtk_validate(struct phylink_
+ 		if (MTK_HAS_CAPS(mac->hw->soc->caps, MTK_SGMII)) {
+ 			phylink_set(mask, 1000baseT_Full);
+ 			phylink_set(mask, 1000baseX_Full);
++			phylink_set(mask, 2500baseT_Full);
+ 			phylink_set(mask, 2500baseX_Full);
+ 		}
+ 		if (MTK_HAS_CAPS(mac->hw->soc->caps, MTK_RGMII)) {