[PATCH] erofs-utils: lib: avoid trailing '\n' in erofs_nbd_get_identifier()

[hudsonZhu]

> 2025年9月5日 11:39，Gao Xiang <hsiangkao at linux.alibaba.com> 写道：
> 
> The trailing '\n' shouldn't be part of backend.
> 
> Fixes: 5d3efc9babf3 ("erofs-utils: mount: enable autoclear for NBD devices")
> Cc: Chengyu Zhu <hudson at cyzhu.com>
> Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>

Tested-by: Chengyu Zhu <hudsonzhu at tencent.com>