io_u: use hw assisted random filling for buffers If we're using refill_buffers and not doing any specific dedupe or verification that requires a persistent buffer via a seed, then we can just use hw assisted crc32c for a nice speedup here. This bumps perf by about 2.4x for me in fill rate on aarch64, and about a 28% improvement on x86-64 (using a 12900K). Signed-off-by: Jens Axboe <axboe@kernel.dk>