drm_hwcomposer: Fix PipelineBindable::BindPipeline

We should assign weak pointer object to really take ownership.

Fixes: cad8e0ca57c2 ("drm_hwcomposer: Introduce DrmDisplayPipeline class")
Signed-off-by: Roman Stratiienko <roman.o.stratiienko@globallogic.com>
diff --git a/drm/DrmDisplayPipeline.cpp b/drm/DrmDisplayPipeline.cpp
index 8a490f8..69d28b3 100644
--- a/drm/DrmDisplayPipeline.cpp
+++ b/drm/DrmDisplayPipeline.cpp
@@ -42,6 +42,7 @@
   }
   owner_object = std::make_shared<BindingOwner<O>>(static_cast<O *>(this));
 
+  owner_object_ = owner_object;
   bound_pipeline_ = pipeline;
   return owner_object;
 }