Remove obselete quoting for STFL

The quoting was previously needed because we were directly including the
text in an STFL form specification.
This is no longer necessary now that we use the `stfl_set()` call.

src/formaction.cpp

@@ -599,7 +599,7 @@ void FormAction::start_next_question()
 	 */
 	if (qna_prompts.size() > 0) {
 		f.set("qna_prompt", qna_prompts[0].first);
-		f.set("qna_value", Stfl::quote(qna_prompts[0].second));
+		f.set("qna_value", qna_prompts[0].second);
 
 		f.set("show_qna_label", "1");
 		f.set("show_qna_input", "1");