driver: sensor: npcx: add 'thr-sel' prop. for adc comparator

Add `thr-sel` prop. to select the relevant threshold register for adc
comparator since there're two adc modules in npcx4 series.

Signed-off-by: Kate Yen <htyen@nuvoton.com>
Signed-off-by: Mulin Chao <mlchao@nuvoton.com>