ActiveScreen: improved evaluation of proximity sensor state
Strangely enough, some devices like Moto G use non-zero value for
proximity sensor minimum distance (in particular: 3.0 - 100.0).
Since there's no API for finding out minimum prox sensor value to be
used for evaluation, we have to base it on max value which is available.
Rule: prox sensor is covered when value reported is lower than 10% of
max range value.