arch: Pull the (Sub)OperandList classes into their own file.

Another step in breaking down the isa parser into more manageable parts.

Change-Id: I0c5e70fe481bd17c0069b768129731e99a93ed0d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/35816
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
3 files changed