buffet: Fix default config for device kind

Updated device kind to 'vendor' in buffet's config
to match the latest state of GCD spec.

BUG=None
TEST=`FEATURES=test emerge-link buffet`

Change-Id: I5539771d74ad1932b1df755dc6986343c5438461
Reviewed-on: https://chromium-review.googlesource.com/266395
Trybot-Ready: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Vitaly Buka <vitalybuka@chromium.org>
Commit-Queue: Vitaly Buka <vitalybuka@chromium.org>

buffet/buffet_config.h

diff --git a/buffet/buffet_config.h b/buffet/buffet_config.h
index 05545e0..64c936f 100644
--- a/buffet/buffet_config.h
+++ b/buffet/buffet_config.h
@@ -52,7 +52,7 @@
   std::string oem_name_{"Chromium"};
   std::string model_name_{"Brillo"};
   std::string model_id_{"AAAAA"};
-  std::string device_kind_{"AA"};
+  std::string device_kind_{"vendor"};
   uint64_t polling_period_ms_{7000};
 
   DISALLOW_COPY_AND_ASSIGN(BuffetConfig);