This fixes decoding of certain 7.1 DTS-HD HRA files, as well as matches the spec better.
Table 6-22 in the DTS spec labels the two channels "Left/Right surround on side", and not rear.
Reviewed-by: Benjamin Larsson <benjamin@southpole.se>
Reviewed-by: Nick Brereton <nick@nbrereton.net>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>