third_party/fiat: mark as Static

Bug: 538471522, 538007082
Change-Id: I48e5c796fc24c31b765dd72759a0a102d941728b
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/99507
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Auto-Submit: Jiewei Qian <qjw@google.com>
Commit-Queue: Jiewei Qian <qjw@google.com>

third_party/fiat/README.chromium

diff --git a/third_party/fiat/README.chromium b/third_party/fiat/README.chromium
index 383024b..3d11732 100644
--- a/third_party/fiat/README.chromium
+++ b/third_party/fiat/README.chromium
@@ -6,7 +6,7 @@
 License: Apache-2.0
 License File: LICENSE
 Security Critical: yes
-Update Mechanism: Manual
+Update Mechanism: Static (https://crbug.com/538471522)
 Shipped: yes
 
 Description: