drm/amdgpu/gfx9: add golden setting for vega12 (v3)

Add gfx9_2_1 golden setting.

v2: switch to soc15_program_register_sequence for
golden setting programming
v3: squash in additional golden updates

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Feifei Xu <Feifei.Xu@amd.com>
Reviewed-by: Ken Wang <ken.wang@amd.com>
Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>