[PATCH] fix sched_setscheduler semantics

Currently, a negative policy argument passed into the
'sys_sched_setscheduler()' system call, will return with success.  However,
the manpage for 'sys_sched_setscheduler' says:

EINVAL The scheduling policy is not one of the recognized policies, or the
              parameter p does not make sense for the policy.

Signed-off-by: Jason Baron <jbaron@redhat.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>