do not apply profiled vignette correction if the correction mode is set to 'None'

Fixes #4480

rtengine/rawimagesource.cc

@@ -1798,7 +1798,7 @@ void RawImageSource::preprocess  (const RAWParams &raw, const LensProfParams &le
     }
 
     // Correct vignetting of lens profile
-    if (!hasFlatField && lensProf.useVign) {
+    if (!hasFlatField && lensProf.useVign && lensProf.lcMode != LensProfParams::LcMode::NONE) {
         std::unique_ptr<LensCorrection> pmap;
         if (lensProf.useLensfun()) {
             pmap = LFDatabase::findModifier(lensProf, idata, W, H, coarse, -1);