greybus: camera: fix data-connection handling

Now that core supports offloaded connections, we can remove the hack
that was used to setup the data connection.

Note that offloaded-resource management may need to be refined later,
but the current minimal implementation is enough to allow core to manage
the connections (e.g. needed for proper connection tear down and power
management).

This will also allow the camera driver to be converted to a bundle
driver.

Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>