Allow init to update /metadata/tradeinmode/wipe

This is needed to move trade-in mode's first stage code to second-stage
init.

Bug: 411739129
Test: adb shell tradeinmode testing wipe
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:75f43fcfdd56a78617474a3ee3533349a6810005)
Merged-In: I9d41722420b36f1afe84ba8e6baac7aa0276995a
Change-Id: I9d41722420b36f1afe84ba8e6baac7aa0276995a
diff --git a/private/init.te b/private/init.te
index 6f0ee80..7f4585d 100644
--- a/private/init.te
+++ b/private/init.te
@@ -807,6 +807,9 @@
 # allow disk tuning
 allow init rootdisk_sysdev:file create_file_perms;
 
+# Allow updating the trade-in mode wipe indicator.
+allow init tradeinmode_metadata_file:file rw_file_perms;
+
 ###
 ### neverallow rules
 ###