VS compiler complains converting UINTN to UINT16 causes data lost.
Add typecast to fix the build failure.
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Andrdw Fish <afish@apple.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>