[media] drx-j: Fix qam/256 mode
[media] drx-j: Fix qam/256 mode

QAM/256 currently doesn't work, as the code is only called if
channel->mirror is DRX_MIRROR_AUTO, but a prevous if prevents
this condition to happen.

While here, returns -EINVAL to not supported QAM modes and
simplify the code, reducing the number of indents.

Acked-by: Devin Heitmueller <039f3b3c9b432027eb8868e4a734444e1ca005b6@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <0cae1d1e981e84d16b82ca3d17be8a7f826608d3@samsung.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs