fixed SPIR-V constant swizzling

Bug: skia:
Change-Id: I27ccb48351eab7faa46ba65d0c4ec26592da383d
Reviewed-on: https://skia-review.googlesource.com/c/195122
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
1 file changed