Create a file structure which was used to save the memory address for
ITCT cache at debugfs. This structure is bound to the corresponding debugfs
file, it can help callback function of debugfs file to get what it needs.

Link: https://lore.kernel.org/r/1571926105-74636-14-git-send-email-john.garry@huawei.comSigned-off-by: NLuo Jiaxing <luojiaxing@huawei.com>
Signed-off-by: NJohn Garry <john.garry@huawei.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>