drm/amdgpu: add psp support for dimgrey_cavefish(v2)

General psp support for dimgrey_cavefish.

v2: remove the checks for asd load and reroute ih.

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