drm/amd/amdgpu: fix potential memleak

In function amdgpu_get_xgmi_hive, when kobject_init_and_add failed
There is a potential memleak if not call kobject_put.

Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Bernard Zhao <bernard@vivo.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>