platform/x86: asus-wmi: support middle fan custom curves

Adds support for fan curves defined for the middle fan which
is available on some ASUS ROG laptops.

Signed-off-by: Luke D. Jones <luke@ljones.dev>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230630053552.976579-4-luke@ljones.dev


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