ipa: libipa: Pass a reference instead of pointer to Algorithm::process()

Frame contexts will become the core component of IPA modules, always
available to functions of the algorithms. To indicate and prepare for
this, turn the frame context pointer passed to Algorithm::process() into
a reference.

The RkISP1 IPA module doesn't use frame contexts yet, so pass a dummy
context for now.

While at it, drop an unneeded [[maybe_unused]] from Agc::process() and
add a missing parameter documentation for the frameContext argument to
Awb::process().

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

src/ipa/rkisp1/algorithms/awb.cpp

@@ -152,7 +152,7 @@ void Awb::queueRequest(IPAContext &context,
  * \copydoc libcamera::ipa::Algorithm::process
  */
 void Awb::process([[maybe_unused]] IPAContext &context,
-		  [[maybe_unused]] IPAFrameContext *frameCtx,
+		  [[maybe_unused]] IPAFrameContext &frameCtx,
 		  const rkisp1_stat_buffer *stats)
 {
 	const rkisp1_cif_isp_stat *params = &stats->params;