SecurityPkg: Correct misspelled variable name

Fix the misspelled variable name `mTcg2ConfigPrivateDate` and rename it
to `mTcg2ConfigPrivateData` to improve code readability and
maintainability.

The word "Date" (calendar date) was incorrectly used instead of "Data"
(information data).

Signed-off-by: lijunwei <542095246@qq.com>