Since we indirect all of our PMU IRQ handling through a dispatcher, it's
trivial to hook up perf_sample_event_took to prevent applications such
as oprofile from generating interrupt storms due to an unrealisticly
low sample period.
Reported-by: NRobert Richter <rric@kernel.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>