drm/amdgpu: enable RAP TA load

Enable the RAP TA loading path and add RAP test
trigger interface.

v2: fix potential mem leak issue

Signed-off-by: Wenhui Sheng <Wenhui.Sheng@amd.com>
Reviewed-by: Guchun Chen <Guchun.Chen@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>