engines/filecreate: set data direction for stats

engines/filecreate: set data direction for stats

When we init the engine, use whatever data direction the job has
for the latency we log. This means that we're no longer dependent
on the job file setting rw=read/randread or not setting it at all.

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