Keystore 2.0: Enforce MAX_BOOT_LEVEL in software

Test: Initialize keystore.boot_level in init.rc; then
      adb setprop keystore.boot_level 40 and check logs
Test: Test program creates key with MAX_BOOT_LEVEL tag; ensure
      it can be used before bumping keystore.boot_level but not after
Bug: 176450483
Change-Id: I94ea178e0fd524bf0a5d65b016559ddd7766205f
diff --git a/keystore2/src/globals.rs b/keystore2/src/globals.rs
index e1b41b5..04bfbc9 100644
--- a/keystore2/src/globals.rs
+++ b/keystore2/src/globals.rs
@@ -160,7 +160,7 @@
     /// priorities.
     pub static ref ASYNC_TASK: Arc<AsyncTask> = Default::default();
     /// Singleton for enforcements.
-    pub static ref ENFORCEMENTS: Enforcements = Enforcements::new();
+    pub static ref ENFORCEMENTS: Enforcements = Default::default();
     /// LegacyBlobLoader is initialized and exists globally.
     /// The same directory used by the database is used by the LegacyBlobLoader as well.
     pub static ref LEGACY_BLOB_LOADER: Arc<LegacyBlobLoader> = Arc::new(LegacyBlobLoader::new(