kconfig: allow build-time definition of the internal config prefix

Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Michal Marek <mmarek@suse.cz>
diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
index d56131c..d6cfa0f 100644
--- a/scripts/kconfig/conf.c
+++ b/scripts/kconfig/conf.c
@@ -425,7 +425,7 @@
 		    (sym_is_choice(sym) && sym_get_tristate_value(sym) == yes)) {
 			if (input_mode == listnewconfig) {
 				if (sym->name && !sym_is_choice_value(sym)) {
-					printf("CONFIG_%s\n", sym->name);
+					printf("%s%s\n", CONFIG_, sym->name);
 				}
 			} else if (input_mode != oldnoconfig) {
 				if (!conf_cnt++)