greybus: core: add bundle id to bundle uevents

Add the bundle id to bundle uevents.

This is needed to identify bundles that are being removed (e.g. at
hot-unplug).

Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>