drm/amdgpu: Add psp 11.0 support for vega20. (v2)

Add psp 11.0 code for vega20 and enable it.  PSP is the
security processor for the GPU.  It handles firmware
loading and GPU resets among other things.

v2: whitespace fix, enable support, adjust reg includes (Alex)

Signed-off-by: Feifei Xu <Feifei.Xu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>