Remove unused template

Previously, code does not compile if using Post(fence) method. Error
message is no matching member function for call to 'Post',
frameworks/native/libs/vr/libbufferhub/include/private/dvr/buffer_hub_client.h:217:7:
note: candidate template ignored: couldn't infer template argument
'Meta'.

Test: use Post method in test and build on oc-dr1-daydream-dev branch.
Bug: None
Change-Id: Icc6977ec6b805d062cb3d0289c73fbf8b43ec940
diff --git a/libs/vr/libbufferhub/buffer_hub-test.cpp b/libs/vr/libbufferhub/buffer_hub-test.cpp
index 2ab5b65..37b9a03 100644
--- a/libs/vr/libbufferhub/buffer_hub-test.cpp
+++ b/libs/vr/libbufferhub/buffer_hub-test.cpp
@@ -593,7 +593,7 @@
 
   LocalHandle fence;
 
-  EXPECT_EQ(0, p->Post<void>(LocalHandle()));
+  EXPECT_EQ(0, p->Post(LocalHandle()));
   EXPECT_EQ(0, c->Acquire(&fence));
 }