ksmbd: retry iterate_dir in smb2_query_dir

Some file systems do not ensure that the single call of iterate_dir
reaches the end of the directory. For example, FUSE fetches entries from
a daemon using 4KB buffer and stops fetching if entries exceed the
buffer. And then an actor of caller, KSMBD, is used to fill the entries
from the buffer.
Thus, pattern searching on FUSE, files located after the 4KB could not
be found and STATUS_NO_SUCH_FILE was returned.

Signed-off-by: Hobin Woo <hobin.woo@samsung.com>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Tested-by: Yoonho Shin <yoonho.shin@samsung.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>