Properly clean the sysfs entries in the error path

Cc: <stable@vger.kernel.org>
Reported-by: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>