sdm: hwc2: Fix Concurrent Writeback issues

1. Clear Output buffer fb_id cache on Concurrent Writeback teardown.
2. Set the Handle Id of Output buffer for Concurrent Writeback.
3. In HWC binder thread for Output layer dump, do not allocate the
   new Output buffer, if the buffer already exists.

CRs-Fixed: 2315986
Change-Id: Ica37cc580f7aab0d13bcb80f5f81a8e1c9678ce1
2 files changed