platform/x86: thinkpad_acpi: add P1 gen3 second fan support

Tested on my P1 gen3, works fine with `thinkfan`. Since thinkpad_acpi fan
control is off by default, it is safe to add 2nd fan control for brave
overclockers

Signed-off-by: Iakov 'Jake' Kirilenko <jake.kirilenko@gmail.com>
Link: https://lore.kernel.org/r/20201105152556.34073-1-jake.kirilenko@gmail.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>