Fix regression of wrong min value on night display slice

The min value of NightDisplayIntensityPreferenceController
should always be 0 (which is the old value we used before
ag/7062353). The range is cacluated from the relative value
to MinimumColorTemperature, which means the min value should
always be 0.

Test: atest NightDisplayIntensityPreferenceControllerTest
Fixes:130758028
Change-Id: Ica75672dda6a9ee0c6013f1c903611263b7d133f