Remove unused HSV and LAB matrix conversion from C (#9724)

Author: radarhere

src/libImaging/Matrix.c

@@ -46,9 +46,7 @@ ImagingConvertMatrix(Imaging im, const ModeID mode, float m[]) {
             }
         }
         ImagingSectionLeave(&cookie);
-    } else if (
-        mode == IMAGING_MODE_HSV || mode == IMAGING_MODE_LAB || mode == IMAGING_MODE_RGB
-    ) {
+    } else if (mode == IMAGING_MODE_RGB) {
         imOut = ImagingNewDirty(mode, im->xsize, im->ysize);
         if (!imOut) {
             return NULL;