This PR implements FEAT_MPAM on the CPU side. We define a MPAM system
registers and a mechanism
for tagging memory requests with the MPAM information bundle as
specified in existing documentation [1].
What this PR is *not* covering is the MPAM implementation in a MSC
(Memory System Component).
Which means at the moment it's only possible to have static partitioning
schemes (via the PartitioningPolicies
already part of gem5) and there is currently no way to dynamically
program partitions at runtime.
[1]: https://developer.arm.com/documentation/ddi0487/latest/
10b24dc9a4