cmd/internal/obj/ppc64: Fix ADUFFxxxx generation on aix/ppc64

ADUFFCOPY and ADUFFZERO instructions weren't handled by rewriteToUseTOC.
These instructions are considered as a simple branch except with -dynlink
where they become an indirect call.

Fixes #34604

Change-Id: I16ca6a152164966fb9cbf792219a8a39aad2b53b
Reviewed-on: https://go-review.googlesource.com/c/go/+/197842


Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>