Like its predecessors Aldebran also supports advanced high bandwidth
GPU-GPU communication interface known as xgmi. This enables the basic
xgmi support while refactoring the code slightly.

Detection of xgmi link between host cpu and gpu will be introduced in a
different patch.
Reviewed-by: NOak Zeng <oak.zeng@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: NHawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: NRajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>