drm/amdgpu: add PSP KDB loading support for Arcturus

Add support for the arcturus specific psp metadata to the
amdgpu firmware and properly parse it when loading it.

Signed-off-by: John Clements <john.clements@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>