block/rnbd-clt-sysfs: fix a couple uninitialized variable bugs

These variables are printed on the error path if match_int() fails so
they have to be initialized.

Fixes: 2958a995 ("block/rnbd-clt: Support polling mode for IO latency optimization")
Fixes: 1eb54f8f

 ("block/rnbd: client: sysfs interface functions")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Gioh Kim <gi-oh.kim@ionos.com>
Link: https://lore.kernel.org/r/20211012084443.GA31472@kili


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