tracing: extend sched_pi_setprio

tracing: extend sched_pi_setprio

Use the TRACE_EVENT_MAP macro to extend the sched_pi_setprio into
sched_pi_update_prio. The pre-existing event is untouched. This gets rid
of the old/new prio fields, and instead outputs the scheduling update
based on the top waiter of the rtmutex.

Boosting:
sched_pi_update_prio: comm=lowprio1, pid=3818, old_policy=SCHED_NORMAL,
	old_nice=0, old_rt_priority=0, old_dl_runtime=0,
	old_dl_deadline=0, old_dl_period=0, top_waiter_comm=highprio0,
	top_waiter_pid=3820, new_policy=SCHED_FIFO, new_nice=0,
	new_rt_priority=90, new_dl_runtime=0, new_dl_deadline=0,
	new_dl_period=0

Unboosting:
sched_pi_update_prio: comm=lowprio1, pid=3818, old_policy=SCHED_FIFO,
	old_nice=0, old_rt_priority=90, old_dl_runtime=0, old_dl_deadline=0,
	old_dl_period=0, top_waiter_comm=, top_waiter_pid=-1,
	new_policy=SCHED_NORMAL, new_nice=0, new_rt_priority=0,
	new_dl_runtime=0, new_dl_deadline=0, new_dl_period=0

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt (Red Hat) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>