kconfig: rename SYMBOL_AUTO to SYMBOL_NO_WRITE

Over time, the use of the flag SYMBOL_AUTO changed from initially
marking three automatically generated symbols ARCH, KERNELRELEASE and
UNAME_RELEASE to today's effect of protecting symbols from being
written out.

Currently, only symbols of type CHOICE and those with option
defconf_list set have that flag set.

Reflect that change in semantics in the flag's name.

Signed-off-by: Dirk Gouders <dirk@gouders.net>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/scripts/kconfig/zconf.y b/scripts/kconfig/zconf.y
index 4b68272..96081aa 100644
--- a/scripts/kconfig/zconf.y
+++ b/scripts/kconfig/zconf.y
@@ -265,7 +265,7 @@
 choice: T_CHOICE word_opt T_EOL
 {
 	struct symbol *sym = sym_lookup($2, SYMBOL_CHOICE);
-	sym->flags |= SYMBOL_AUTO;
+	sym->flags |= SYMBOL_NO_WRITE;
 	menu_add_entry(sym);
 	menu_add_expr(P_CHOICE, NULL, NULL);
 	free($2);