drm/amdgpu: add initial GC 11.0.2 support

Add initial support for GC 11.0.2 to gfx_v11_0.c.

Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Flora Cui <flora.cui@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>