ide: clear ide_req()->special for non-passthrough requests

ide: clear ide_req()->special for non-passthrough requests

The initial patch cleared this for all requests, which is wrong
since internal uses can't have this cleared as that's what they
are using to pass data. The fix moved the initialization to the
mq_ops->initialize_rq_fn(), but that's only a partial fix since
it only catches uses from blk_get_request(), not requests coming
from the file system.

Keep the non-fs initialization, and add the IDE entry clear
IFF RQF_DONTPREP isn't set and it's a passthrough request.

Fixes: d16a67667c61 ("ide: don't clear special on ide_queue_rq() entry")
Fixes: 22ce0a7ccf23 ("ide: don't use req->special")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Jens Axboe <axboe@kernel.dk>