drm/amdgpu: fix hive reference leak when adding xgmi device

Only amdgpu_get_xgmi_hive but no amdgpu_put_xgmi_hive
which will leak the hive reference.

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