In current code sensor driver registers all 4 sensors together and if
any of them has not bound to thermal zone successfully then driver will
return failure for driver's initialization. As a result, if DT binds
thermal zone with only one sensor, then the thermal driver will not work
well anymore.

So this patch is to fix this issue. It allows the thermal sensor driver
can register any number sensors at initialization phase, and fix up code
for other related code to skip related sensor's accessing if the sensor
has not been enabled in initialization phase.
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>