perf: arm_cspmu: Support implementation specific validation

Some platforms may use e.g. different filtering mechanism and, thus,
may need different way to validate the events and group.

Signed-off-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230913233941.9814-4-ilkka@os.amperecomputing.com


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