thermal: Use generic HW-protection shutdown API

The hardware shutdown function was exported from kernel/reboot for
other subsystems to use. Logic is copied from the thermal_core. The
protection mutex is replaced by an atomic_t to allow calls also from
an IRQ context. Also the WARN() was replaced by pr_emerg() based on
discussions here:
https://lore.kernel.org/lkml/YJuPwAZroVZ%2Fw633@alley/
and here:
https://lore.kernel.org/linux-iommu/20210331093104.383705-4-geert+renesas@glider.be/



Use the exported API instead of implementing own just for the
thermal_core.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/5531e89d9e710f5d10e7cdce3ee58957335b9e03.1622628333.git.matti.vaittinen@fi.rohmeurope.com


Signed-off-by: Mark Brown <broonie@kernel.org>