kconfig: Don't leak choice names during parsing

The named choice is not used in the kernel tree, but if it were used,
it would not be freed.

The intention of the named choice can be seen in the log of
commit 5a1aa8a ("kconfig: add named choice group").

Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Ulf Magnusson <[email protected]>

scripts/kconfig/zconf.y

@@ -276,6 +276,7 @@ choice: T_CHOICE word_opt T_EOL
 	sym->flags |= SYMBOL_AUTO;
 	menu_add_entry(sym);
 	menu_add_expr(P_CHOICE, NULL, NULL);
+	free($2);
 	printd(DEBUG_PARSE, "%s:%d:choice\n", zconf_curname(), zconf_lineno());
 };