[$] A deadline scheduler update

The deadline CPU scheduler has come a long way, Juri Lelli said in his 2017Linaro Connect session, but there is still quite a bit of work to be done.While this scheduler was originally intended for realtime workloads, there isreason to believe that it is well suited for other settings, including theembedded and mobile world. In this talk, he gave a summary of what thedeadline scheduler provides now and the changes that are envisioned for thenear (and not-so-near) future.