thermal: allow registering without .get_temp

This patch changes the thermal core driver to allow
registration of thermal zones without the .get_temp callback.

The idea behind this change is to allow lazy registration
of sensor callbacks.

The thermal zone will be disabled whenever the ops
does not contain a .get_temp callback. The sysfs interface
will be returning -EINVAL on any temperature read operation.

Cc: Zhang Rui <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Eduardo Valentin <[email protected]>
1 file changed