platform/x86: thinkpad_acpi: Add quirk for ThinkPads without a fan

Some ThinkPad models, like the X1 Tablet 1st and 2nd Gen, are passively
cooled without any fan.  Currently, an entry in /proc/acpi/ibm/fan is
nevertheless created, and misleadingly shows
	status:		enabled
	speed:		65535
	level:		auto

This patch adds a TPACPI_FAN_NOFAN quirk definition and corresponding
handling to not initialize a fan interface at all.

For the time being, the quirk is only applied for X1 Tablet 2nd Gen
(types 20JB, 20JC; EC N1O...); further models (such as Gen1, types 20GG
and 20GH) can be added easily once tested.

Tested on a 20JCS00C00, BIOS N1OET58W (1.43), EC N1OHT34W.

Signed-off-by: Alexander Kobel <a-kobel@a-kobel.de>
Link: https://lore.kernel.org/r/12d4b825-a2b9-8cb7-6ed3-db4d66f46a60@a-kobel.de
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
1 file changed