vfio/migration - delete a dbg function

driver inclusion
category: cleanup
bugzilla: https://gitee.com/openeuler/kernel/issues/I8LFYK


CVE: NA

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Deleted a dbug function because this function has the risk of
address leakage. In addition, this function is only used for
debugging in the early stage and is not required in the future.

Signed-off-by: Chenghai Huang <huangchenghai2@huawei.com>
Signed-off-by: JiangShui Yang <yangjiangshui@h-partners.com>