Uic: fix crash when trying to resource icon information

Fix a typo introduced in be56db2c49be02fd7083c5a02131462748e29bef to
avoid a crash when a pixmap is given for selected on but not for
selected off.

Fixes: QTBUG-79125
Change-Id: I84072b6b4e8a4d21684be21f5bff1deeaddbba6d
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

src/tools/uic/cpp/cppwriteinitialization.cpp

@@ -1680,7 +1680,7 @@ static void writeResourceIcon(QTextStream &output,
                          "Selected", "Off");
     }
     if (i->hasElementSelectedOn()) {
-        writeIconAddFile(output, indent, iconName, i->elementSelectedOff()->text(),
+        writeIconAddFile(output, indent, iconName, i->elementSelectedOn()->text(),
                          "Selected", "On");
     }
 }