arch-arm,cpu: Add a class for ops for vec reg elements.

This lets a caller print the name of a register in a friendly way
without having to know how many elements go with each vector register.

Change-Id: I85598c078c604f1bebdba797308102482639c209
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/49163
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
3 files changed