[path-bar] Fix mx_path_bar_clear
[path-bar] Fix mx_path_bar_clear

We were using the list of children instead of the current level integer
in the while loop. This was causing an infinite loop, as the crumbs
actually being removed from the list requires an animation to complete.

jonnylamb/mx,clutter-project/mx,clutter-project/mx,pwithnall/mx,jonnylamb/mx,jonnylamb/mx,jonnylamb/mx,pwithnall/mx,pwithnall/mx,clutter-project/mx,pwithnall/mx,clutter-project/mx