ARM perf events spin locks

[Will Deacon]

> Hi Will,

Hello,

> I think we should convert the spinlocks in the ARM perf events code to raw
> spinlocks for realtime. Should we wait for your split set to get merged first
> before doing this?

Since this is a logically separate change, I think we're better off waiting
until the split stuff has been merged. As for the raw spinlocks, by realtime
do you mean PREEMPT_RT? Also, do we actually *need* raw spinlocks in the perf
code?

Will