smb/server: Fix another refcount leak in smb2_open()

smb/server: Fix another refcount leak in smb2_open()

If ksmbd_override_fsids() fails, we jump to err_out2. At that point, fp is
NULL because it hasn't been assigned dh_info.fp yet, so ksmbd_fd_put(work,
fp) will not be called. However, dh_info.fp was already inserted into the
session file table by ksmbd_reopen_durable_fd(), so it will leak in the
session file table until the session is closed.

Move fp = dh_info.fp; ahead of the ksmbd_override_fsids() check to fix the
problem.

Found by an experimental AI code review agent at Google.

Fixes: c8efcc786146a ("ksmbd: add support for durable handles v1/v2")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>