graphics: fix readback buffer tests

Make readback buffer support optional.  Fix incorrect use of
setReadbackBuffer and getReadbackBufferFence.

Bug:  80030364
Test: VTS
Change-Id: I278a031c3c086ac38c460b7076a2952db57a91a4
Merged-In: I278a031c3c086ac38c460b7076a2952db57a91a4
diff --git a/graphics/composer/2.2/utils/vts/ComposerVts.cpp b/graphics/composer/2.2/utils/vts/ComposerVts.cpp
index 357c772..6a32071 100644
--- a/graphics/composer/2.2/utils/vts/ComposerVts.cpp
+++ b/graphics/composer/2.2/utils/vts/ComposerVts.cpp
@@ -45,6 +45,10 @@
     return client;
 }
 
+sp<V2_2::IComposerClient> ComposerClient_v2_2::getRaw() const {
+    return mClient_v2_2;
+}
+
 std::vector<IComposerClient::PerFrameMetadataKey> ComposerClient_v2_2::getPerFrameMetadataKeys(
     Display display) {
     std::vector<IComposerClient::PerFrameMetadataKey> keys;