zyd_gct_set_channel_synth
error = zyd_gct_set_channel_synth(rf, 1, 0);
error = zyd_gct_set_channel_synth(rf, 1, 1);
error = zyd_gct_set_channel_synth(rf, chan, 0);
static int zyd_gct_set_channel_synth(struct zyd_rf *, int, int);