If we do not have a fan it does not make sense to load curves for it.
This removes the following warnings from the kernel log:

asus_wmi: fan_curve_get_factory_default (0x00110024) failed: -19
asus_wmi: fan_curve_get_factory_default (0x00110025) failed: -19

Fixes: a2bdf10c ("platform/x86: asus-wmi: Increase FAN_CURVE_BUF_LEN to 32")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20221221-asus-fan-v1-3-e07f3949725b@weissschuh.netReviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>