file-utilities: Do not use default location instead of root
The default location (i.e. g_mount_get_default_location) should be used when opening mounted, but we should not use it instead of the root button in the path bar. Because it is currently impossible to navigate to parent folders if default location is set. Let's change nautilus_get_mounted_mount_for_root logic and return mount only for root path so we can see the real root in the path bar.