Bug 7170947 Configure AAC decoder for mobile DRC settings

Configure the AAC decoder to use the modile DRC settings when
 decoding streams with DRC metadata.
 Settings are:
 - target reference level of -12dB
 - DRC compression factor (attenuation) at max
These settings can be overridden by platform properties if the
 default values are to be modified.

Change-Id: If329fe566497685b735abe4e4b9a5e01697c063b