There is no need to keep the dentry around for the debugfs trace files,
as we can just look it up when we want to remove it later on.  Simplify
the structure by removing the dentries and relying on debugfs to find
the dentry to remove when we want to.

By doing this change, we remove the last in-kernel user that was storing
the result of debugfs_create_bool(), so that api can be cleaned up.

Cc: Karan Tilak Kumar <kartilak@cisco.com>
Cc: Sesidhar Baddela <sebaddel@cisco.com>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: <linux-scsi@vger.kernel.org>
Link: https://lore.kernel.org/r/20210518161625.3696996-1-gregkh@linuxfoundation.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>