perf/arm-cmn: Move IRQs when migrating context

If we migrate the PMU context to another CPU, we need to remember to
retarget the IRQs as well.

Fixes: 0ba64770 ("perf: Add Arm CMN-600 PMU driver")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/e080640aea4ed8dfa870b8549dfb31221803eb6b.1611839564.git.robin.murphy@arm.com


Signed-off-by: Will Deacon <will@kernel.org>