Allow independent tuner decimation for each channel on a GC4016. This is only appropriate for CPC=2 and CPC=4 configurations. Do NOT use with CPC=1. Currently the ITDEC mode reduces the tuner output dynamic range from 96 to 84 dB. The lower 4 bits of each data word contain the channel number. This also requires sharc CPU cycles to demux the packets on PIC4/MBT4 cards.