drm/amdgpu: Reconfigure ULV for gfx9 server SKUs

SDMA ULV can benefit low-power modes, but can sometimes cause
latency increases in small SDMA transfers. Server SKUs have a
different trade-off space in this domain, so this configures
the server SKUs' ULV hysteresis times differently than consumer
SKUs'.

Signed-off-by: Joseph Greathouse <Joseph.Greathouse@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>