libcamera: libipa: camera_sensor_helper: add IMX290 black level

Report the default sensor black level reported by the datasheet.
Note that IMX327 and IMX462 depend on the IMX290 CameraSensorHelper.
That's fine since those sensors report the same defaults for the
black level as the Sony IMX290.

Signed-off-by: Geoffrey Van Landeghem <geoffrey.vl@gmail.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>

src/ipa/libipa/camera_sensor_helper.cpp

@@ -576,6 +576,8 @@ class CameraSensorHelperImx290 : public CameraSensorHelper
 public:
 	CameraSensorHelperImx290()
 	{
+		/* From datasheet: 0xf0 at 12bits. */
+		blackLevel_ = 3840;
 		gainType_ = AnalogueGainExponential;
 		gainConstants_.exp = { 1.0, expGainDb(0.3) };
 	}