tracepoint: trace_sched_migrate_task(): remove parameter

tracepoint: trace_sched_migrate_task(): remove parameter

The orig_cpu parameter in trace_sched_migrate_task() is not necessary,
it can be got by using task_cpu(p) in the probe.

[ Impact: micro-optimization ]

Signed-off-by: Mathieu Desnoyers <[email protected]>
[ modified from Mathieu's patch. The original patch is at:
  http://marc.info/?l=linux-kernel&m=123791201716239&w=2 ]
Signed-off-by: Xiao Guangrong <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Li Zefan <[email protected]>
Cc: [email protected]
Cc: [email protected]
LKML-Reference: <49FFFDB7.1050402@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <[email protected]>