This patch is to add gfx golden settings for vangogh post si.

v2: squash in updates
v3: fix SPI register offset
Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>