bus: cci: move away from arm_pmu framework

The ARM CPU PMUs and the ARM CCI PMU are using the same framework
despite being substantially different in programming model, which makes
it difficult to handle either particularly well.

This patch migrates the ARM CCI PMU driver away from the arm_pmu
framework, matching the style of the CCN PMU driver and other 'uncore'
PMU drivers. This will enable refactoring of the arm_pmu framework to
better support CPU PMUs. Event context migration on hotplug is not yet
added due to a race on event->ctx in the core perf code.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
[will: fix whitespace issues]
Signed-off-by: Will Deacon <will.deacon@arm.com>