arm64: perf_events: Allow edac to use the pmu interrupt

In the event that edac driver needs to use the percpu
pmu interrupt, the PMU driver should relinquish
control over the interrupt. The edac driver takes the
responsibilty of invoking the pmu interrupt handler
if a non-edac pmu event triggers the pmu interrupt.
This is synchronized using a global variable.

Change-Id: I21274377cb51b890e0bfb2f05d601c49dd0b9f73
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>