Revert "Change the stem name to microdroid_precompiled_sepolicy"

Revert submission 2625691

Reason for revert: b/287283650

Reverted changes: /q/submissionid:2625691

Change-Id: I775d07a388556796d25b4f5d99135d5878489ce8
diff --git a/microdroid/Android.bp b/microdroid/Android.bp
index f24f31d..12bb8f7 100644
--- a/microdroid/Android.bp
+++ b/microdroid/Android.bp
@@ -233,7 +233,7 @@
 
 se_policy_binary {
     name: "microdroid_precompiled_sepolicy",
-    stem: "microdroid_precompiled_sepolicy",
+    stem: "precompiled_sepolicy",
     srcs: [
         ":microdroid_plat_sepolicy.cil",
         ":microdroid_plat_mapping_file",