hwc: Add support to query CWB support.

CRs-Fixed: 2607415
Change-Id: I5e0e084d5b25884652e799ac09c558c79c73edd3
diff --git a/composer/hwc_display_builtin.cpp b/composer/hwc_display_builtin.cpp
index eaee590..8d3bb4e 100644
--- a/composer/hwc_display_builtin.cpp
+++ b/composer/hwc_display_builtin.cpp
@@ -1317,4 +1317,11 @@
   return 0;
 }
 
+bool HWCDisplayBuiltIn::HasReadBackBufferSupport() {
+  DisplayConfigFixedInfo fixed_info = {};
+  display_intf_->GetConfig(&fixed_info);
+
+  return fixed_info.readback_supported;
+}
+
 }  // namespace sdm