perf/x86: Remove redundant calls to perf_pmu_{dis|en}able()

perf_pmu_disable() is called before pmu->add() and perf_pmu_enable() is called
afterwards. No need to call these inside of x86_pmu_add() as well.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1424281543-67335-1-git-send-email-dsahern@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/cpu/perf_event.c

@@ -1044,7 +1044,6 @@ static int x86_pmu_add(struct perf_event *event, int flags)
 
 	hwc = &event->hw;
 
-	perf_pmu_disable(event->pmu);
 	n0 = cpuc->n_events;
 	ret = n = collect_events(cpuc, event, false);
 	if (ret < 0)
@@ -1082,7 +1081,6 @@ done_collect:
 
 	ret = 0;
 out:
-	perf_pmu_enable(event->pmu);
 	return ret;
 }