Remove function visitor dimension check
Remove function visitor dimension check

We weren't visiting constraints on dimensions beyond the fourth,
probably because that used to be the limit on a buffer_t. Removed. Done
as a PR for testing in case I'm missing something.

psuriana/Halide,psuriana/Halide,kgnk/Halide,kgnk/Halide,psuriana/Halide,psuriana/Halide,kgnk/Halide,kgnk/Halide,kgnk/Halide,psuriana/Halide,kgnk/Halide,psuriana/Halide,psuriana/Halide,kgnk/Halide,kgnk/Halide