Drop long unused exynos private u-boot tree

This repo is not used anymore, no need to keep checking for it when
looking for project specific hooks.

BUG=none
TEST=none

Change-Id: I5fba8771c381b46ec07be1c784e7eda1947abbb2
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/205170
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/pre-upload.py b/pre-upload.py
index 704cf3e..e067eeb 100755
--- a/pre-upload.py
+++ b/pre-upload.py
@@ -885,7 +885,6 @@
     "chromeos/third_party/intel-framework": [_check_change_has_branch_field],
     "chromeos/vendor/kernel-exynos-staging": [_run_checkpatch,
                                               _kernel_configcheck],
-    "chromeos/vendor/u-boot-exynos": [_run_checkpatch_no_tree],
     "chromiumos/overlays/board-overlays": [_check_manifests],
     "chromiumos/overlays/chromiumos-overlay": [_check_manifests],
     "chromiumos/overlays/portage-stable": [_check_manifests],