thermal/drivers/tegra: Correct compile-testing of drivers

All Tegra thermal drivers support compile-testing, but the drivers are
not available for compile-testing because the whole Kconfig meny entry
depends on ARCH_TEGRA, missing the alternative COMPILE_TEST dependency
option. Correct the Kconfig entry.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210617072403.3487-1-digetx@gmail.com