drm/amdgpu fix incorrect sysfs remove behavior for xgmi

Under xgmi setup,some sysfs fail to create for the second time of kmd
driver loading. It's due to sysfs nodes are not removed appropriately
in the last unlod time.

Changes of this patch:
1. remove sysfs for dev_attr_xgmi_error
2. remove sysfs_link adev->dev->kobj with target name.
   And it only needs to be removed once for a xgmi setup
3. remove sysfs_link hive->kobj with target name

In amdgpu_xgmi_remove_device:
1. amdgpu_xgmi_sysfs_rem_dev_info needs to be run per device
2. amdgpu_xgmi_sysfs_destroy needs to be run on the last node of
device.

v2: initialize array with memset

Signed-off-by: Jack Zhang <Jack.Zhang1@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>