arm-cci: Abstract the CCI400 PMU specific definitions

CCI400 has different event specifications for PMU, for revsion
0 and revision 1. As of now, we check the revision every single
time before using the parameters for the PMU. This patch abstracts
the details of the pmu models in a struct (cci_pmu_model) and
stores the information in cci_pmu at initialisation time, avoiding
multiple probe operations.

Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>