IntelFsp2Pkg/GenCfgOpt.py: Support UPD offset auto assignment
    
    REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1211
    
    For reducing maintenance effort, the UPD offset can be
    automatic assigned by GenCfgOpt.py following by alignment
    requirements.
    
    The usage model as below:
    . If UPD offset in DSC file are all '*', GenCfgOpt.py will
      assign offset for all UPD automatically. In this case no
      need to manually hardcode offset to all UPD in DSC.
    
    . If UPD offset in DSC file are all not '*', GenCfgOpt.py
      will use hardcoded offset directly (original usage model)
    
    . Tool does not support mixing scenario so UPD offset in DSC
      should be all '*' or all hardcoded but not mixed.
    
    In auto mode UPD offset will be assigned following natural
    alignment (size aligned) rule and the whole structure size
    will align to either 32bits or 64bits depends on maximal UPD
    size in the structure.
    
    Test: Verified by both UPD offset hardcoded or '*' in DSC and
          generated UPD header files are correct.
    
    Cc: Jiewen Yao <Jiewen.yao@intel.com>
    Cc: Gao Liming <liming.gao@intel.com>
    Cc: Zhu Yonghong <yonghong.zhu@intel.com>
    Contributed-under: TianoCore Contribution Agreement 1.1
    Signed-off-by: Chasel Chiu <chasel.chiu@intel.com>
    Reviewed-by: Jiewen Yao <Jiewen.yao@intel.com>