cmd/compile: adopt strong aux typing for some s390x rules

Convert some optimizations rules to strongly-typed versions. So far, I
have only converted the rules that need no additional changes (i.e: only
need to change '->' to "=>").

This CL covers the rules from line 478 - line 800 in S390X.rules file.
Some compare and branch rules also fall in this range, but they were
already done previously in another CL.

Passes toolstash-check.
Change-Id: I9167c5f1a32f4fd6c29bacc13fff95e83b0533e0
Reviewed-on: https://go-review.googlesource.com/c/go/+/230338


Reviewed-by: Michael Munday <mike.munday@ibm.com>
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>