kconfig: remove 'const' from the return type of sym_escape_string_value()

sym_escape_string_value() returns a malloc'ed memory, but as
(const char *). So, it must be casted to (void *) when it is free'd.
This is odd.

The return type of sym_escape_string_value() should be (char *).

I exploited that free(NULL) has no effect.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
index cf72680..9b2271e 100644
--- a/scripts/kconfig/confdata.c
+++ b/scripts/kconfig/confdata.c
@@ -728,21 +728,22 @@ static struct conf_printer header_printer_cb =
 static void conf_write_symbol(FILE *fp, struct symbol *sym,
 			      struct conf_printer *printer, void *printer_arg)
 {
-	const char *str;
+	const char *val;
+	char *escaped = NULL;
 
-	switch (sym->type) {
-	case S_UNKNOWN:
-		break;
-	case S_STRING:
-		str = sym_get_string_value(sym);
-		str = sym_escape_string_value(str);
-		printer->print_symbol(fp, sym, str, printer_arg);
-		free((void *)str);
-		break;
-	default:
-		str = sym_get_string_value(sym);
-		printer->print_symbol(fp, sym, str, printer_arg);
+	if (sym->type == S_UNKNOWN)
+		return;
+
+	val = sym_get_string_value(sym);
+
+	if (sym->type == S_STRING) {
+		escaped = sym_escape_string_value(val);
+		val = escaped;
 	}
+
+	printer->print_symbol(fp, sym, val, printer_arg);
+
+	free(escaped);
 }
 
 static void