Use sp<> on creating BufferHubBinderService

The original code implicitly calls the constructor of sp<> in
addService() function call, which is not good for readability. Replace
it with sp<> could improve readability and avoid possible memory leak if
the implementation detail of sp<> changes.

Test: atest buffer_hub_binder_service-test (passed)
Bug: 115429751
Change-Id: Ice304a638b8d353a3b229e48c17ecd6f32a66f37
diff --git a/services/vr/bufferhubd/buffer_hub_binder.cpp b/services/vr/bufferhubd/buffer_hub_binder.cpp
index b507717..de82c09 100644
--- a/services/vr/bufferhubd/buffer_hub_binder.cpp
+++ b/services/vr/bufferhubd/buffer_hub_binder.cpp
@@ -13,7 +13,7 @@
     const std::shared_ptr<BufferHubService>& pdx_service) {
   IPCThreadState::self()->disableBackgroundScheduling(true);
 
-  BufferHubBinderService* service = new BufferHubBinderService();
+  sp<BufferHubBinderService> service = new BufferHubBinderService();
   service->pdx_service_ = pdx_service;
 
   // Not using BinderService::publish because need to get an instance of this