arm64: defconfig: Enable MediaTek DWMAC

Enable the config for the DWMAC MediaTek glue layer to allow usage of
the Ethernet controller present on MT8195 and MT8188 SoCs.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Link: https://lore.kernel.org/r/20241216-genio700-configs-eth-sound-v1-2-04a719035d6e@collabora.com
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

arch/arm64/configs/defconfig

@@ -375,6 +375,7 @@ CONFIG_SMSC911X=y
 CONFIG_SNI_AVE=y
 CONFIG_SNI_NETSEC=y
 CONFIG_STMMAC_ETH=m
+CONFIG_DWMAC_MEDIATEK=m
 CONFIG_DWMAC_TEGRA=m
 CONFIG_TI_K3_AM65_CPSW_NUSS=y
 CONFIG_TI_ICSSG_PRUETH=m