Extend D127824 to the 32-bit Power architecture.
AFAICT GNU objdump -d dumps all instructions for 32-bit as well.
Reviewed By: #powerpc, nemanjai
Differential Revision: https://reviews.llvm.org/D155114
GNU objdump disassembles all unknown instructions by default. Match this user
friendly behavior with the cpu value `future`.
Differential Revision: https://reviews.llvm.org/D127824