smb/client: zero-initialize stack-allocated cifs_open_info_data

Stack-allocated cifs_open_info_data may contain random data.
This can make some fields have wrong value if they are not set later.

Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>