Plugin should always look in /sys/closed-loop for data files regardless of M505 setting

If M505 is used to select a subfolder of /sys for configuration files, then the plugin fails to find the collected data files. They are always stored in /sys/closed-loop regardless of any use of M505.

Fixed in 3.4.0. The file list reads 0:/sys/closed-loop/ directly instead of deriving the
path from the configured system directory, so M505 no longer affects it. Still the case in
the 3.7.0 rewrite.