ipa: Pass metadata to Algorithm::process() function

Extend the Algorithm::process() function with a metadata control list,
to be filled by individual algorithms with frame metadata. Update the
rkisp1 and ipu3 IPA modules accordingly, and drop the dead code in the
IPARkISP1::prepareMetadata() function while at it.

This only creates the infrastructure, filling metadata in individual
algorithms will be handled separately.

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/ipu3/algorithms/agc.cpp

@@ -320,13 +320,15 @@ double Agc::estimateLuminance(IPAActiveState &activeState,
  * \param[in] frame The current frame sequence number
  * \param[in] frameContext The current frame context
  * \param[in] stats The IPU3 statistics and ISP results
+ * \param[out] metadata Metadata for the frame, to be filled by the algorithm
  *
  * Identify the current image brightness, and use that to estimate the optimal
  * new exposure and gain for the scene.
  */
 void Agc::process(IPAContext &context, [[maybe_unused]] const uint32_t frame,
 		  IPAFrameContext &frameContext,
-		  const ipu3_uapi_stats_3a *stats)
+		  const ipu3_uapi_stats_3a *stats,
+		  [[maybe_unused]] ControlList &metadata)
 {
 	/*
 	 * Estimate the gain needed to have the proportion of pixels in a given