kconfig: send error messages to stderr

These messages should be directed to stderr.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Ulf Magnusson <ulfalizer@gmail.com>
diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
index 13f7fdf..c4409ee 100644
--- a/scripts/kconfig/symbol.c
+++ b/scripts/kconfig/symbol.c
@@ -1221,7 +1221,7 @@ static struct symbol *sym_check_expr_deps(struct expr *e)
 	default:
 		break;
 	}
-	printf("Oops! How to check %d?\n", e->type);
+	fprintf(stderr, "Oops! How to check %d?\n", e->type);
 	return NULL;
 }