drm/amdkfd: report the numa weight between host and device over xgmi

GPUs connected to CPUs over xGMI are bidirectional so set weight by a
single hop both ways.

Signed-off-by: Jonathan Kim <jonathan.kim@amd.com>
Tested-by: Ramesh Errabolu <ramesh.errabolu@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>