The PCIe speed capabilities advertised by a USB4 or TBT3 link are
limited to PCIe gen 1 per the USB4 spec. In reality the speed will
change dynamically based on fabric conditions and other traffic.

DPM is disabled when dGPUs are connected directly to Intel hosts
since the PCIe root port isn't able to handle dynamic speed
switching.

As this limitation is specifically for PCIe root ports in the SoC,
don't apply it when connected to an eGPU enclosure connected to an
Intel host.

Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2885Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>