Remove unused MediaDrm.unprovisionDevice

bug:25726218
Change-Id: Id45b4d509ab6b9db01c749af6533521992d89452
diff --git a/include/media/drm/DrmAPI.h b/include/media/drm/DrmAPI.h
index 272881b..985d919 100644
--- a/include/media/drm/DrmAPI.h
+++ b/include/media/drm/DrmAPI.h
@@ -220,9 +220,6 @@
                                                   Vector<uint8_t> &certificate,
                                                   Vector<uint8_t> &wrapped_key) = 0;
 
-        // Remove device provisioning.
-        virtual status_t unprovisionDevice() = 0;
-
         // A means of enforcing the contractual requirement for a concurrent stream
         // limit per subscriber across devices is provided via SecureStop.  SecureStop
         // is a means of securely monitoring the lifetime of sessions. Since playback