Delete HWC2to1Adapter unused code.

HWC2to1Adapter supports forwarding Display requests from device
to client. However hwc1 does not support the request.

Change-Id: Id2e77b18823d319721473b3a8c8838aa20b7daec
diff --git a/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.cpp b/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.cpp
index 40c6715..1727bd6 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.cpp
@@ -808,7 +808,10 @@
         return Error::None;
     }
 
-    *outDisplayRequests = mChanges->getDisplayRequests();
+    // Display requests (HWC2::DisplayRequest) are not supported by hwc1:
+    // A hwc1 has always zero requests for the client.
+    *outDisplayRequests = 0;
+
     uint32_t numWritten = 0;
     for (const auto& request : mChanges->getLayerRequests()) {
         if (numWritten == *outNumElements) {