greybus: bundles: remove gb_bundle(s)_init()

They aren't used anymore, remove them. This also gets rid of
gb_bundle_connections_init().

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