drm/amdgpu: share drm device for pci amdgpu device with 1st partition device

To save render node resoure, share drm device setting for pci amdgpu
device with 1st XCP partition device.

Signed-off-by: James Zhu <James.Zhu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>