Revert "sched: Add 'flags' argument to sched_{set,get}attr() syscalls"

This reverts commit 088af0e9. Including
this commit causes crashes during audio-playback. Investigation is
underway as to the root cause, but until the issue is fully understood
this commit should be excluded.

Change-Id: I3f6289d6249de5f7080f3fefba6a17a5f569eeac
Signed-off-by: Ian Maund <imaund@codeaurora.org>