buffet: Save save buffet state on UpdateDeviceInfo call

Buffet needs to save state as soon as possible when basic info is
updated. Save() call should be added by CL:266206.

BUG=brillo:377
TEST=FEATURES=test emerge-gizmo buffet

Change-Id: I38e620340d04ba2ae2e261c8d7af244c76910a01
Reviewed-on: https://chromium-review.googlesource.com/268684
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Vitaly Buka <vitalybuka@chromium.org>
Commit-Queue: Vitaly Buka <vitalybuka@chromium.org>

buffet/device_registration_info.cc

diff --git a/buffet/device_registration_info.cc b/buffet/device_registration_info.cc
index eec9985..136513d 100644
--- a/buffet/device_registration_info.cc
+++ b/buffet/device_registration_info.cc
@@ -767,6 +767,8 @@
   config_->set_description(description);
   config_->set_location(location);
 
+  Save();
+
   OnConfigChanged();
 
   if (HaveRegistrationCredentials(nullptr)) {