Remove BootControlInterface::PreparePartitionsForUpdate

Replace with GetDynamicPartitionControl()->PreparePartitionsForUpdate(
GetCurrentSlot(), ...).

Test: update_engine_unittests
Change-Id: Ib03ee97a25727a9292cbb0c9aab5dbe75a2b6913
diff --git a/payload_consumer/delta_performer.cc b/payload_consumer/delta_performer.cc
index 8b3f61c..f9244a9 100644
--- a/payload_consumer/delta_performer.cc
+++ b/payload_consumer/delta_performer.cc
@@ -947,8 +947,11 @@
 bool DeltaPerformer::PreparePartitionsForUpdate() {
   bool metadata_updated = false;
   prefs_->GetBoolean(kPrefsDynamicPartitionMetadataUpdated, &metadata_updated);
-  if (!boot_control_->PreparePartitionsForUpdate(
-          install_plan_->target_slot, manifest_, !metadata_updated)) {
+  if (!boot_control_->GetDynamicPartitionControl()->PreparePartitionsForUpdate(
+          boot_control_->GetCurrentSlot(),
+          install_plan_->target_slot,
+          manifest_,
+          !metadata_updated)) {
     LOG(ERROR) << "Unable to initialize partition metadata for slot "
                << BootControlInterface::SlotName(install_plan_->target_slot);
     return false;