thermal: int340x: Fix unexpected shutdown at critical temperature

thermal: int340x: Fix unexpected shutdown at critical temperature

We are seeing thermal shutdown on Intel based mobile workstations, the
shutdown happens during the first trip handle in
thermal_zone_device_register():
kernel: thermal thermal_zone15: critical temperature reached (101 C), shutting down

However, we shouldn't do a thermal shutdown here, since
1) We may want to use a dedicated daemon, Intel's thermald in this case,
to handle thermal shutdown.

2) For ACPI based system, _CRT doesn't mean shutdown unless it's inside
ThermalZone namespace. ACPI Spec, 11.4.4 _CRT (Critical Temperature):
"... If this object it present under a device, the device’s driver
evaluates this object to determine the device’s critical cooling
temperature trip point. This value may then be used by the device’s
driver to program an internal device temperature sensor trip point."

So a "critical trip" here merely means we should take a more aggressive
cooling method.

As int340x device isn't present under ACPI ThermalZone, override the
default .critical callback to prevent surprising thermal shutdown.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20201221172345.36976-1-kai.heng.feng@canonical.com