Get excelsior manifest from coral instead of aiyprojects

Change-Id: I64b97fe22e6bc4a2d18566368f3f3b808da34b54
diff --git a/vars/functions.groovy b/vars/functions.groovy
index cce19a2..be727da 100644
--- a/vars/functions.groovy
+++ b/vars/functions.groovy
@@ -81,7 +81,6 @@
 def manifestUrlFromBoardName(boardName) {
     switch (boardName) {
         case "excelsior":
-            return "http://aiyprojects.googlesource.com/manifest"
         case "enterprise":
             return "http://coral.googlesource.com/manifest"
         default: