aaccoder_mips: update function definitions

This commit updates the function definitions in the aaccoder_mips.c
file. This was broken around a month or so ago with the addition
of the rounding argument.
The previous commit in this series also introduced a separate array
to put the quantization error in, this also needed to be updated,
albeit non-functional, in the MIPS optimized aaccoder file.

Credits for the rounding goes to Claudio Freire.
Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>