thermal: armada: use the resource managed registration helper alternative

Current use of thermal_zone_device_register() triggers a warning at boot
and should be replaced by devm_thermal_zone_of_sensor_register(). This
allows better handling of multiple thermal zones for later multi-sensors
support.

Also change the driver data to embed a new structure to make the
difference between legacy data (which needs to be cleaned) and
syscon-related data.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>