arm64: defconfig: Enable Tegra SoC Thermal driver

Enable the Tegra SoC Thermal driver that is used by Tegra132 and
Tegra210 platforms to be built as a module by default for ARM64 builds.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>