platform/x86: thinkpad_acpi: Fix invalid fan speed on ThinkPad X120e

platform/x86: thinkpad_acpi: Fix invalid fan speed on ThinkPad X120e

[ Upstream commit 1046cac109225eda0973b898e053aeb3d6c10e1d ]

On ThinkPad X120e, fan speed is reported in ticks per revolution
rather than RPM.

Recalculate the fan speed value reported for ThinkPad X120e
to RPM based on a 22.5 kHz clock.

Based on the information on
https://www.thinkwiki.org/wiki/How_to_control_fan_speed,
the same problem is highly likely to be relevant to at least Edge11,
but Edge11 is not addressed in this patch.

Signed-off-by: Sybil Isabel Dorsett <sybdorsett@proton.me>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20250203163255.5525-1-sybdorsett@proton.me
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>