Volume section defines a volume curve for a given use case and device category.
It contains a list of points of this curve expressing the attenuation in Millibels
for a given volume index from 0 to 100.
0,-9600
100,0
It may also reference a reference/@name to avoid duplicating curves.
0,-9600
100,0
Comma separated pair of number.
The fist one is the framework level (between 0 and 100).
The second one is the volume to send to the HAL.
The framework will interpolate volumes not specified.
Their MUST be at least 2 points specified.