greybus: bundle: add activate and deactivate

AP shall send the Bundle Activate Operation to power on a bundle, and
send the Bundle Deactivate Request after closing all the associated
connections for power down.

Testing Done:
 - Check for the return code of the bundle activate and deactivate
  operation sent

Signed-off-by: David Lin <dtwlin@google.com>
Signed-off-by: Axel Haslam <ahaslam@baylibre.com>
Reviewed-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Alex Elder <elder@linaro.org>