platform/x86: thinkpad_acpi: Add X1 Carbon Gen 9 second fan support

The X1 Carbon Gen 9 uses two fans instead of one like the previous
generation. This adds support for the second fan. It has been tested
on my X1 Carbon Gen 9 (20XXS00100) and works fine.

Signed-off-by: Til Jasper Ullrich <tju@tju.me>
Link: https://lore.kernel.org/r/20210525150950.14805-1-tju@tju.me
Signed-off-by: Hans de Goede <hdegoede@redhat.com>