arm64: defconfig: Enable serial-tegra driver

This driver is used to service the serial ports found on NVIDIA Tegra
SoCs.
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm64/configs/defconfig

@@ -116,6 +116,7 @@ CONFIG_SERIAL_SAMSUNG=y
 CONFIG_SERIAL_SAMSUNG_UARTS_4=y
 CONFIG_SERIAL_SAMSUNG_UARTS=4
 CONFIG_SERIAL_SAMSUNG_CONSOLE=y
+CONFIG_SERIAL_TEGRA=y
 CONFIG_SERIAL_MSM=y
 CONFIG_SERIAL_MSM_CONSOLE=y
 CONFIG_SERIAL_OF_PLATFORM=y