Fixup: tdx-compliance: Fix some cases and related pre-condition funct…

…ion.

According to the latest TDX v1.5 specifications, certain adjustments are required in some cases and related pre-condition function to prevent false failures.

Signed-off-by: Dongcheng Yan <dongcheng.yan@intel.com>

PT test: Add 20 PT cases with perf tool.

Signed-off-by: Ammy Yi <ammy.yi@intel.com>

th: Fix the warning complaint that occurred during compilation.

Add a header for function 'close'.
Replace 'strncpy' with 'memcpy'.
Remove an unnecessary declaration.

Signed-off-by: Yi Sun <yi.sun@intel.com>

Add README for project LKVS.

Add README.md in the root folder for project LKVS, which includes the features
introduction, usage, contribution rules and licenses.

Reviewed-by: Wendy Wang <wendy.wang@intel.com>
Reviewed-by: Pengfei Xu <pengfei.xu@intel.com>
Signed-off-by: Yi Sun <yi.sun@intel.com>