that's dependent on how you have coreboot set to initialize the screen. Are you using a VBIOS by chance?
I'm using the coreboot driver. It's a UEFI only build.
I suspect https://github.com/MrChromebox/edk2/commit/cd5b08f9aa34a255c3b39c996a0f47609... but I didn't see it in the coreboot_fb branch. Maybe I should get froggy and merge upstream into tianocore.