Fork vboot_reference in manifest

We need to fork vboot_reference to carry custom patches for signing
behavior.

BUG=b/170128847
TEST=repo init and repo sync
RELEASE_NOTE=None

Change-Id: I7afe7f22b9426364c931cd0f76eb4918849a7fd6
Reviewed-on: https://cos-review.googlesource.com/c/cos/manifest/+/15493
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Tested-by: Dexter Rivera <riverade@google.com>
diff --git a/external_full.xml b/external_full.xml
index 18439e7..7d898ba 100644
--- a/external_full.xml
+++ b/external_full.xml
@@ -36,9 +36,6 @@
   <project path="src/platform/crostestutils"
            name="mirrors/cros/chromiumos/platform/crostestutils"
            revision="7666ad6d68f381a9de17d682c01803ca2f1c985d" />
-  <project path="src/platform/vboot_reference"
-           name="mirrors/cros/chromiumos/platform/vboot_reference"
-           revision="6f6efdc6fa38ed3bcacfa9e152f415d50ee8bad0" />
   <project path="src/third_party/autotest/files"
            name="mirrors/cros/chromiumos/third_party/autotest"
            revision="db48601acf9d646e8f4b4c223e67da2d40cf02e6" />
@@ -83,6 +80,9 @@
   <project path="chromite"
            name="third_party/chromite"
            revision="refs/heads/main" />
+  <project path="src/platform/vboot_reference"
+           name="third_party/platform/vboot_reference"
+           revision="refs/heads/main" />
   <project path="src/repohooks"
            name="cos/repohooks" />
   <project path="src/platform/cobble"