drm/amdgpu: change psp_rap_invoke() function return value

RAP TA is an optional firmware. if it doesn’t exist,
the driver should bypass psp_rap_invoke() function.

1. bypass psp_rap_invoke() when RAP TA is not loaded.
2. add new parameter (status) to query RAP TA status.
   (the status value is different with psp_ta_invoke(),
3. fix the 'rap_status' MThread critical problem.
   (used without lock)

Signed-off-by: Kevin Wang <kevin1.wang@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>