Revert "Temporarily disable checkstyle hook"

This reverts commit 8497789b3b3f78e8eec53e946654afd896436c60.

Reason for revert: This was fixed, see b/160796554

Bug: 160796554
Change-Id: I42f8d6b76c7319522239517ac3aff6eee7d9084b
diff --git a/PREUPLOAD.cfg b/PREUPLOAD.cfg
index 9b290c6..2fd2e33 100644
--- a/PREUPLOAD.cfg
+++ b/PREUPLOAD.cfg
@@ -12,6 +12,8 @@
                services/incremental/
 
 [Hook Scripts]
+checkstyle_hook = ${REPO_ROOT}/prebuilts/checkstyle/checkstyle.py --sha ${PREUPLOAD_COMMIT}
+
 strings_lint_hook = ${REPO_ROOT}/frameworks/base/tools/stringslint/stringslint_sha.sh ${PREUPLOAD_COMMIT}
 
 hidden_api_txt_checksorted_hook = ${REPO_ROOT}/frameworks/base/tools/hiddenapi/checksorted_sha.sh ${PREUPLOAD_COMMIT} ${REPO_ROOT}