Delete simple repeat code

Delete simple repeat code

This was supposedly an optimization, but it has pathological cases
where it definitely isn't. For example a 1 x n image will cause it to
have terrible memory access patterns and to generate a ton of modulus
operations.

Since no one has ever measured whether it actually is an improvement,
and since it is doing the repeating at the wrong the stage in the
pipeline, and since with the previous commit it can't be triggered
anymore because we now require SAMPLES_COVER_CLIP for regular fast
paths, just delete it.