thermal: Make sysfs attributes of cooling devices default attributes

Default attributes are created when the device is registered. Attributes
created after device registration can lead to race conditions, where user space
(e.g. udev) sees the device but not the attributes.

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
(cherry picked from commit 2dc10f8963e6a03a1a75deafe1d1984bafab08dd)
Signed-off-by: Kevin Hilman <khilman@linaro.org>