CSD: Add interface for attenuating the MEL

The sound dose interface allows to set an attenuation used in the
internal MEL computation. This can be used for example when absolute
volume mode is used.

Test: dumpsys and logs
Bug: 265928284
Change-Id: If1d2c44dd670f9a63249bf7ce6c48e1cc509bcc9
Merged-In: If1d2c44dd670f9a63249bf7ce6c48e1cc509bcc9