arch-arm: Re-factor Arm decoder for SVE mixed-sign DOT insts.

Re-factored the Arm instruction decoder to add placeholders for the
SVE Integer mixed-sign DOT product instructions. This has involved
moving some existing decode helper functions.

Change-Id: I42b280d4bd1b4ab9d8c633bdc523bd08c281d218
Reviewed-by: Richard Cooper <richard.cooper@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/70731
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
2 files changed