drm/amdgpu: Re-enable VCN RAS if DPG is enabled

VCN RAS enablement sequence needs to be added in
DPG HW init sequence.

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>