Remove unused adjusted_ichannels

[yutannihilation]

I added adjusted_ochannels and adjusted_ichannels in #90, but later it turned out these are unnecessary, so adjusted_ochannels was removed in #91. It's still unclear what the implementation for input will be, but I bet adjusted_ichannels can be removed for now for consistency.

[tomoyanonymous]

Thanks. I think it looks OK.

Passing input signal to dsp code is the next task. Maybe similar variables will be needed again when the input and output channels are different.

[yutannihilation]

Maybe similar variables will be needed again when the input and output channels are different.

Oh, thanks. I don't see the whole picture, but I roughly thought

1. the input / output channels of a DSP code is determined based on the code and inference from hardware.
2. if there is some mismatch between the number of channels of the hardware and that of the DSP code, fill the extra channels with zero like Fixed the crush and glitch in multiple output channels #91 did.

So, I expected a variable like adjusted_ichannels is not necessary. But, I don't get how a mismatch between input and output can matter, so I think my understanding is not enough at the moment.

Anyway, leaving the variable is no harm, so I'm fine with closing this pull request.