sub_f32 -> sub_f32_imm more sanely

Change-Id: Ic89359cd08298e73011952452ce909291d6f3fe9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/269947
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed