drm/amd/pm: Add gpu_metrics_v1_8

Add new gpu_metrics_v1_8 to acquire below host limit counters

Signed-off-by: Asad Kamal <asad.kamal@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>