greybus: bundle: separate connection disabling and destruction

Separate bundle-connection disabling and destruction, and destroy the
connections along with the bundle.

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>