Add pre-upload hook to check xml file formatting

Change-Id: I57df002a0f412726449a6dbd2a32b01a234b3b4d
Test: atest :postsubmit --include-subdirs
diff --git a/PREUPLOAD.cfg b/PREUPLOAD.cfg
index b097da5..948fa79 100644
--- a/PREUPLOAD.cfg
+++ b/PREUPLOAD.cfg
@@ -2,6 +2,7 @@
 bpfmt = true
 google_java_format = true
 pylint = true
+xmllint = true
 
 [Hook Scripts]
 checkstyle_hook = ${REPO_ROOT}/prebuilts/checkstyle/checkstyle.py