greybus: camera: HACK: Export GB camera interface

Gb camera need to communicate with HOST driver.
as temporary solution there will be shared header
between gb camera HOST camera.
Both need to be in sync since gb drivers are compiled
out of the kernel tree.

Gb camera register camera operation functions when is created.
Currently unregister is not supported.

Signed-off-by: Gjorgji Rosikopulos <grosikopulos@mm-sol.com>
Acked-by: Laurent Pinchart <laurent.pinchart@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>