ipa: rpi: Replace dropFrameCount in the IPA -> PH interface

Replace the dropFrameCount parameter returned from ipa::start() to the
pipeline handler by startupFrameCount and invalidFrameCount. The former
counts the number of frames required for AWB/AGC to converge, and the
latter counts the number of invalid frames produced by the sensor when
starting up.

In the pipeline handler, use the sum of these 2 values to replicate the
existing dropFrameCount behaviour.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/pipeline/rpi/common/pipeline_base.cpp

@@ -660,8 +660,8 @@ int PipelineHandlerBase::start(Camera *camera, const ControlList *controls)
 		data->setSensorControls(result.controls);
 
 	/* Configure the number of dropped frames required on startup. */
-	data->dropFrameCount_ = data->config_.disableStartupFrameDrops
-			      ? 0 : result.dropFrameCount;
+	data->dropFrameCount_ = data->config_.disableStartupFrameDrops ?
+			0 : result.startupFrameCount + result.invalidFrameCount;
 
 	for (auto const stream : data->streams_)
 		stream->resetBuffers();