cpusets: update maintainers

Update CPUSETS MAINTAINERS to reflect the more active role of Paul Menage
(secondary to his work on cgroups) and the retirement of the original author
of cpusets, Simon Derr.  Thanks, Simon!  Best of luck to you.

Signed-off-by: Paul Jackson <pj@sgi.com>
Acked-by: Paul Menage <menage@google.com>
Acked-by: Simon Derr <simon.derr@bull.net>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>