Start removing uses of VkFormatToPixelConfig in vulkan backend

Bug: skia:
Change-Id: I2c8e86b9e8ca6a33913be347a3c65af963c5fd12
Reviewed-on: https://skia-review.googlesource.com/84341
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
5 files changed