nvmet: filter newlines from user input

We should avoid consuming the newlines in traddr, trsvcid and
device_path. Add minimal processing to make sure they are gone.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>