The commit on amd-staging-drm-next I checked out for verification is:

Author:     Shaoyun Liu <Shaoyun.Liu@amd.com>
AuthorDate: Tue May 22 11:45:41 2018 -0400
Commit:     Alex Deucher <alexander.deucher@amd.com>
CommitDate: Thu May 24 10:28:35 2018 -0500

    drm/amdgpu: Update GFX info structure to match what vega20 used

    Update to the latest version from the vbios team.

    Signed-off-by: Shaoyun Liu <Shaoyun.Liu@amd.com>
    Acked-by: Alex Deucher <alexander.deucher@amd.com>
    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

It was working for me to directly checkout the commit and build. It is 4.16-rc7
build.