ACPI / fan: do nothing in suspend and poweroff callback

We put fans to full speed in acpi_fan_suspend(), but that is only
needed in the hibernation case when we are generating hibernation
image, so this patch removes that when we are about to suspend or
poweroff.

References: http://www.spinics.net/lists/linux-acpi/msg48636.html


Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>