Fix read and write forms for angle_RGBx textures.

Test in the bug are still failing when using RGBx for write and
read pixels when going through angle vulkan swiftshader. It is
still not clear where in the stack the data is getting messed up.
But at least for now it seems good to at least update the Skia code
here to use the correct enums as required by the spec, https://chromium.googlesource.com/angle/angle/+/refs/heads/main/extensions/ANGLE_rgbx_internal_format.txt

Bug: b/246008627
Change-Id: I1819d36899bfc44b87186500b6330fb61933b506
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/599358
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
1 file changed