IntelFsp2Pkg: Align #Pragma in UPD header files to rest of EDK2 Pkgs

Changed the GenCfgOpt.py script to insert pragma pack(1) instead of
pragma pack (push, 1) in the upd header files generated during fsp build.
This is to align with rest of the EDKII pkgs pragma pack usage.

Also, this scripts generates UnusedUpdSpace for UPD address gaps.
Currently it uses UIN16/UINT32/UINT64 for 2/4/8 bytes instead of UINT8[],
thus causing upd space waste to have Natural Alignment. Hence changed the
script to use UINT8[] for any unusedUpd fields above 1 byte.

Cc: Maurice Ma <maurice.ma@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Giri P Mudusuru <giri.p.mudusuru@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Satya Yarlagadda <satya.p.yarlagadda@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Giri P Mudusuru <giri.p.mudusuru@intel.com>