IntelFsp2Pkg: Locate FSP Info Header dynamically

IntelFsp2Pkg: Locate FSP Info Header dynamically

we need to locate the FSP Info Header by calculating offset dynamically to
handle the scenario of FSP component is being rebased to different location.

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: Maurice Ma <maurice.ma@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Giri P Mudusuru <giri.p.mudusuru@intel.com>