greybus: es2: add support for CDSI1 allocation

Use the new CPort-allocation callbacks to allow for rudimentary resource
management of the CDSI CPorts.

How to manage offloaded resources in a generic fashion is yet to be
determined, but this minimal implementation will allow core to manage
the camera data connection so that the current camera-driver hacks can
be removed. This is specifically required to be able to implement proper
connection closing and for power management.

Note that the CDSI CPorts can not (currently) be reset through the
USB vendor request.

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>