aacdec: Prefer NeAACDecInit() over NeAACDecInit2().

aacdec: Prefer NeAACDecInit() over NeAACDecInit2().

The aac decoder tries to parse the length of the decoder configuration
from the esds atom and passes this information to NeAACDecInit2(). If
we can not figure out the length, we fall back to NeAACDecInit(),
which does not receive the decoder length as a parameter. This is
unnecessary because NeAACDecInit2() is only necessary for decoding
mp4 files, while both para_afh and para_server feed demultiplexed
aac frames to the decoder.

Calling NeAACDecInit() unconditionally allows to get rid of the
code which detects and parses the esds atom.