solaar: fix, partially (close #12685)

vcunat's comments:
Unused parameter got removed.
CLI looks good now but the GUI still won't work with:

bin/..solaar-wrapped-wrapped:45: PyGIWarning:
 Gtk was imported without specifying a version first.
 Use gi.require_version('Gtk', '3.0') before import to ensure that the right version gets loaded.
  solaar.gtk.main()
 solaar: error: Argument 0 does not allow None as a value