ACPI / fan: Improve acpi_device_update_power error message

On my laptop, I see "Setting initial power state" on boot.  It's a
firmware bug on my laptop, but the message made me think that the
initial power state was bogus and the driver fixed it.  The error
actually means that the driver failed to set the initial power
state.  Fix the message.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>