dt-bindings: thermal: convert st,stih407-thermal to DT schema

'st,passive_colling_temp' does not appear in the device-tree, 'reg' and
'#thermal-sensor-cells' are also missing in the device description.

Convert st,stih407-thermal binding to DT schema format in order to clean
unused 'st,passive_cooling_temp' and add missing properties.

Signed-off-by: Raphael Gallais-Pou <rgallaispou@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20240320-thermal-v3-1-700296694c4a@gmail.com