thermal/drivers/hisi: Set the thermal zone private data to the sensor pointer

Store the sensor pointer in the thermal zone private data and use it
in the callback functions. That allows to continue the conversion to
sensor oriented code where the pointers are the sensors.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>