thermal: qoriq: Use devm_thermal_zone_of_sensor_register()

By using the managed devm_thermal_zone_of_sensor_register() we can
drop the explicit call to thermal_zone_of_sensor_unregister() in the
qoriq_tmu_remove() function, which simplifies the code a bit.

So switch to devm_thermal_zone_of_sensor_register().

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>