greybus: manifest: clean up properly when parsing bundles

Currently, if an error occurs creating a bundle, we simply
return an error without cleaning up any of the bundles that
had already been successfully set up.

Add code to destroy bundles that have been created in the event
an error occurs.  Add a check to ensure the interface's list of
bundles was empty before parsing for bundles begins.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>