Capturing and downloading dif command data and dif data was done a dozen
years ago and no longer being used. Also creates a potential security hole.

Remove the debugfs buffer for dif debugging.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
CC: KyleMahlkuch <kmahlkuc@linux.vnet.ibm.com>
CC: Hannes Reinecke <hare@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>