When probing via ACPI, we won't know up-front whether a CPU has a PMUv3
compatible PMU. Thus we need to consult ID registers during probe time.

This patch updates our PMUv3 probing code to test for the presence of
PMUv3 functionality before touching an PMUv3-specific registers, and
before updating the struct arm_pmu with PMUv3 data.

When a PMUv3-compatible PMU is not present, probing will return -ENODEV.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>