SF: remove unused variable on chooseCompositionStrategy.

Change-Id: I941fccb3eccfb37573d350e363c5a34258ff3e84
Signed-off-by: linkai <linkai@xiaomi.com>
diff --git a/services/surfaceflinger/CompositionEngine/src/Display.cpp b/services/surfaceflinger/CompositionEngine/src/Display.cpp
index 85fc095..047250a 100644
--- a/services/surfaceflinger/CompositionEngine/src/Display.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/Display.cpp
@@ -250,7 +250,6 @@
     }
 
     // Get any composition changes requested by the HWC device, and apply them.
-    std::optional<android::HWComposer::DeviceRequestedChanges> changes;
     auto& hwc = getCompositionEngine().getHwComposer();
     const bool requiresClientComposition = anyLayersRequireClientComposition();