io_uring: don't clear recently set sqe->rw_flags

io_uring: don't clear recently set sqe->rw_flags

Commit 7c70f506e438 ("engines/io_uring: move sqe clear out of hot path")
removed the memset of sqe from fio_ioring_prep().

This commit did add a clear of the sqe->rw_flags, however, it did so
after both RWF_UNCACHED and RWF_NOWAIT flags might have been set,
effectively clearing these flags if they got set.

This doesn't make any sense. Make sure that we clear sqe->rw_flags
before, not after, setting the flags.

Fixes: 7c70f506e438 ("engines/io_uring: move sqe clear out of hot path")
Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>