AAC decoder: fix boost/attenuation defaults, loudness norm off

For MPEG-D DRC the default value of the boost and attenuation
factors is 127. For MPEG-4 DRC the default value is 0. In the
current DRC presentation mode wrapper, setting boost or attenuation
factor to 0 doesn't work for MPEG-DRC, use value -1 instead.

Fix Target Reference Level set to -1 as a valid value for disabling
loudness normalization.

Bug: 148385721
Test: atest DecoderTestXheAac DecoderTestAacDrc
Change-Id: I33479072c508b5700c0b35f389802dc17b2b4536