platform/x86: thinkpad_acpi: Fix reporting a non present second fan on some models

thinkpad_acpi was reporting 2 fans on a ThinkPad T14s gen 1, even though
the laptop has only 1 fan.

The second, not present fan always reads 65535 (-1 in 16 bit signed),
ignore fans which report 65535 to avoid reporting the non present fan.

Signed-off-by: Jelle van der Waa <jvanderwaa@redhat.com>
Link: https://lore.kernel.org/r/20221019194751.5392-1-jvanderwaa@redhat.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>