skip _imm ops on ARM

These are really designed around x86, so forcing them
on ARM where our existing non-immediate ops work better
is kind of silly.

Change-Id: I6b66ed0b0a71b335becdcb1d67dec471620542b0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/254440
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
2 files changed