SecurityPkg: Update VariableAuthenticated driver with following changes:

SecurityPkg: Update VariableAuthenticated driver with following changes:

1. Remove memory allocation code in runtime.
2. Exclude NULL terminator in VariableName for serialization data in time-based variable authentication.
3. Add support for enroll PK with WRITE_ACCESS attribute.
4. Initialize SetupMode variable with correct NV attribute.
5. Add support for APPEND_WRITE attribute for non-existing Variable.
6. Clear KEK, DB and DBX as well as PK when user request to clear platform keys.
7. Check duplicated EFI_SIGNATURE_DATA for Variable formatted as EFI_SIGNATURE_LIST when APPEND_WRITE attribute is set.
8. Not change SecureBoot Variable in runtime, only update it in boot time since this Variable indicates firmware operating mode.
9. Save time stamp of PK when PK is set with TIME_BASED_WRITE_ACCESS attribute in setup mode.
10. Update to use PcdMaxVariableSize instead of PcdMaxAppendVariableSize for append operation.

Signed-off-by: xdu2
Reviewed-by: tye
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12599 6f19259b-4bc3-4df7-8a09-765794883524