thermal: rockchip: Add the sort mode for adc value increment or decrement

The conversion table has the adc value and temperature.
In fact, the adc value only has the increment or decrement mode in
conversion table.

Moment, we can add the sort mode to be better support the *code_to_temp*
for differenr SoCs.

Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>