Fix following DTC warnings in cros-adc-thermistors:

Warning (unit_address_vs_reg): Node /adc@12D10000/ncp15wb473@3 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /adc@12D10000/ncp15wb473@4 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /adc@12D10000/ncp15wb473@5 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /adc@12D10000/ncp15wb473@6 has a unit name, but no reg property
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>