Make generate_test_report point at autotest copy

BUG=b:25929635
TEST=`./generate_test_report` prints usage message

CQ-DEPEND=CL:316524

Change-Id: I80f8183bc20473e6c21fe03c0331a3c040624b5d
Reviewed-on: https://chromium-review.googlesource.com/316457
Commit-Ready: Christopher Wiley <wiley@chromium.org>
Tested-by: Christopher Wiley <wiley@chromium.org>
Reviewed-by: Simran Basi <sbasi@chromium.org>
diff --git a/generate_test_report b/generate_test_report
index 1f513f7..b89c4dc 120000
--- a/generate_test_report
+++ b/generate_test_report
@@ -1 +1 @@
-../platform/crostestutils/utils_py/generate_test_report.py
\ No newline at end of file
+../third_party/autotest/files/site_utils/generate_test_report
\ No newline at end of file