IKEA Vallhorn Motion Sensor

[TapioX]

@TapioX

@Mariano_Colmenarejo

Modified ikea Vallhorn subdriver to multiply by 10 the default formula result for illuminance, prior to math.floor

local lux_value = math.floor((math.pow(10, (value.value - 1) / 10000) * 10)

Now lux values are higher.
I will do more tests at some point.

Illuminance calculation is now modified.