drm/amdgpu: add GFX support for ELM/BAF

V2: use gfx_8_0_*.h instead of gfx_8_1_*.h
v3: agd: integrate support for gfx info table
Signed-off-by: Flora Cui <Flora.Cui@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jammy Zhou <Jammy.Zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>