Make GPU configs use kRGBA color type not kN32.

This makes ES msaa contexts testable on systems where kN32 is compiled as kBGRA due to the fact that render buffers are not always supported for GL_BGRA with GL_EXT_texture_format_BGRA8888.

BUG=skia:5804
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2378713002

Review-Url: https://codereview.chromium.org/2378713002
2 files changed