ipa: rkisp1: Move calculation of RGB means into own function

Move the calculation of the RGB means into an own function for better
code clarity. This commit doesn't contain any functional changes.

Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>

src/ipa/rkisp1/algorithms/awb.h

@@ -39,6 +39,9 @@ public:
 		     ControlList &metadata) override;
 
 private:
+	RGB<double> calculateRgbMeans(const IPAFrameContext &frameContext,
+				      const rkisp1_cif_isp_awb_stat *awb) const;
+
 	std::optional<Interpolator<Vector<double, 2>>> colourGainCurve_;
 	bool rgbMode_;
 };