engine/filecreate: use clat and reads for stats

engine/filecreate: use clat and reads for stats

Fio defaults to reads, we should use the same direction as the job
though. Additionally, we must use clat latencies for tracking,
as this is a sync engine and whole latencies are logged as
completions.

Signed-off-by: Jens Axboe <axboe@kernel.dk>