Align Push/PopCallerSaved register list, and remove unused options for two and
three exclusion registers.

Bug: v8:6644
Change-Id: I70df24837b09402e32ddc2a25a3061cd61ec0301
Reviewed-on: https://chromium-review.googlesource.com/790290Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Martyn Capewell <martyn.capewell@arm.com>
Cr-Commit-Position: refs/heads/master@{#49644}