[PATCH v3 2/3] drm/amdgpu: Remove redundant framebuffer format check

[Simon Ser]

Hm, unfortunately I think we need to keep the check in amdgpu for the
same reason as i915: amdgpu will pick a modifier if user-space didn't
supply one on GFX9+.

I wonder if that also applies to vmwgfx? Maybe that would be a reason
to have the check in framebuffer_init()? (Not sure!)