arm64: defconfig: Enable Tegra MGBE driver

Enable the driver for the Multi-Gigabit Ethernet (MGBE) controller which
can be found on NVIDIA Tegra234 SoCs.
Signed-off-by: Bhadram Varka <vbhadram@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm64/configs/defconfig

@@ -354,6 +354,7 @@ CONFIG_SMSC911X=y
 CONFIG_SNI_AVE=y
 CONFIG_SNI_NETSEC=y
 CONFIG_STMMAC_ETH=m
+CONFIG_DWMAC_TEGRA=m
 CONFIG_TI_K3_AM65_CPSW_NUSS=y
 CONFIG_QCOM_IPA=m
 CONFIG_MESON_GXL_PHY=m