Convert the register shifted by immediate form of the data
processing insns. For A32, we cannot yet remove any code
because the legacy decoder intertwines the reg-shifted-reg
and immediate forms.
Backports commit 25ae32c558182c07fc6ad01b936e9151cbf00c44 from qemu
Add the infrastructure that will become the new decoder.
No instructions adjusted so far.
Backports commit 51409b9e8cfe997b1ac3365df7400e0c6e844437 from qemu