ipa: rpi: awb: Disable CT search bias for Grey World AWB

If grey world AWB is setup in the tuning file, the CT curve will either
be missing or invalid. Disable biasing the statistics for the search in
such cases.

Fixes: ea8fd63 ("ipa: rpi: awb: Add a bias to the AWB search")
Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/ipa/rpi/controller/rpi/awb.cpp

@@ -459,10 +459,11 @@ void Awb::prepareStats()
 	 * LSC has already been applied to the stats in this pipeline, so stop
 	 * any LSC compensation.  We also ignore config_.fast in this version.
 	 */
+	const double biasCtR = config_.bayes ? config_.ctR.eval(config_.biasCT) : 0;
+	const double biasCtB = config_.bayes ? config_.ctB.eval(config_.biasCT) : 0;
 	generateStats(zones_, statistics_, config_.minPixels,
 		      config_.minG, getGlobalMetadata(),
-		      config_.biasProportion, config_.ctR.eval(config_.biasCT),
-		      config_.ctB.eval(config_.biasCT));
+		      config_.biasProportion, biasCtR, biasCtB);
 	/*
 	 * apply sensitivities, so values appear to come from our "canonical"
 	 * sensor.