arch: Remove plumbing for an op_idx value in ISA operands.

Now that op_idx is trivial to calculate (just src_reg_idx or
dest_reg_idx), there's no need to have the indirection and extra
mechanism to funnel a precalculated value around.

Change-Id: I37daeb646b85e050c4b832af28d054ecc3c338b1
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/49750
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
3 files changed