As camera object have the potential to outlive the hardware they
represent, there is a need to inform the camera that the underlying
device has been disconnected, and in turn to notify applications.
Implement a disconnection notification mechanism that can be used by
pipeline handlers to notify the camera of disconnection. The camera then
block all new API calls and emit the disconnected signal.
Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>