hwc2: Store output buffer handle correctly

Change-Id: I409b3752d7063baf78e87fc74fa897b5c4ead507
diff --git a/sdm/libs/hwc2/hwc_display_virtual.cpp b/sdm/libs/hwc2/hwc_display_virtual.cpp
index 90e3015..787640c 100644
--- a/sdm/libs/hwc2/hwc_display_virtual.cpp
+++ b/sdm/libs/hwc2/hwc_display_virtual.cpp
@@ -174,6 +174,7 @@
   output_buffer_->acquire_fence_fd = dup(release_fence);
 
   if (output_handle) {
+    output_handle_ = output_handle;
     output_buffer_->buffer_id = reinterpret_cast<uint64_t>(output_handle);
     int output_handle_format = output_handle->format;