Nt32Pkg: Fix code to correctly set SMBIOS Type 2 Length
When running Nt32Pkg, SMBIOS Type 2 had the wrong Length.
Fixed the code to use the correct structure in sizeof, and properly account for ContainedObjectHandles.
Also updated variable names with Assert -> Asset
Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Chris Phillips <chrisp@hpe.com> Reviewed-by: Star Zeng <star.zeng@intel.com>