drm/amdgpu: Add support for CIK parts

This patch adds support for CIK parts. These parts
are also supported by radeon which is the preferred
option, so there is a config option to enable support
for CIK parts in amdgpu for testing.

Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Jammy Zhou <Jammy.Zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>