libcamera: software_isp: blacklevel: Make black level available in debayer params

Populate black level gain in blacklevel::prepare(). A copy is made of the gain
value in the DebayerParams structure.

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/software_isp/debayer.cpp

@@ -105,6 +105,11 @@ namespace libcamera {
  * \brief Per frame colour correction matrix for GPUISP
  */
 
+/**
+ * \var DebayerParams::blackLevel
+ * \brief Blacklevel gains for the GPUISP
+ */
+
 /**
  * \class Debayer
  * \brief Base debayering class