Add servo overlays for excelsior/endeavor

BUG=b:149984996
TEST=sudo servod -b excelsior

Change-Id: I9fd6b0c6dde951ba2f78e2bd808bb1e1588131c3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/hdctools/+/2080671
Reviewed-by: Wai-Hong Tam <waihong@google.com>
Tested-by: Ryan Snyder <turg@google.com>
Commit-Queue: Ryan Snyder <turg@google.com>
diff --git a/servo/servo_interfaces.py b/servo/servo_interfaces.py
index 8ad3f83..e1b469b 100644
--- a/servo/servo_interfaces.py
+++ b/servo/servo_interfaces.py
@@ -310,6 +310,8 @@
     'cheza',
     'dragonegg',
     'drallion',
+    'endeavour',
+    'excelsior',
     'eve',
     'fizz',
     'flapjack',