Almost all of them are, the odd ones out are the poll remove and the
files update request. Name them like the others, which is:

io_#cmdname_prep	for request preparation
io_#cmdname		for request issue
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>