This was suggested by Rodeo on IRC
<Rodeo> for consistency with the rest, MODE_7_1_FRONT_CENTER would be AV_CH_LAYOUT_7POINT1_WIDE_BACK (since LS+RS is mapped to back channels in other modes)
Reviewed-by: Jean First <jeanfirst@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>