drm/amdkfd: map gpu hive id to xgmi connected cpu

ROCr needs to be able to identify all devices that have direct access to
fine grain memory, which should include CPUs that are connected to GPUs
over xGMI. The GPU hive ID can be mapped onto the CPU hive ID since the
CPU is part of the hive.

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