Prevent dead code error on afec::Samples

Why it's unused is a mystery, probably was planned to be returned as multichannel measurement.

Author: michalfita

hal/src/afec.rs

@@ -172,6 +172,7 @@ struct Sample {
 const NUM_CHANNELS: usize = 12;
 
 /// Iterator of [`Sample`]s for enabled and measured channels, from [`Afec::sample`].
+#[allow(dead_code)]
 struct Samples([Option<Sample>; NUM_CHANNELS]);
 impl Iterator for Samples {
     type Item = Sample;