Camera: Add proper buffer drop errors to LEGACY mode

The correct stream ID is required to be sent along with buffer drop
errors, and LEGACY mode was putting in a placeholder.  This would
cause an error in the client-side implementation, triggered by
abortBuffers (Which is the only source of buffer drops from LEGACY).

Bug: 27828602
Change-Id: If3fba7a76f7aa0ff305efa4cce6c225eb720b30e