Keep the per-device dbf entries until module is removed, with
proper error checking for debug feature setup.
Signed-off-by: NStefan Raspl <raspl@linux.vnet.ibm.com>
Reviewed-by: NSteffen Maier <maier@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>