IntelFsp2Pkg: Improve FSP Python scripts to support 3.x.

IntelFsp2Pkg: Improve FSP Python scripts to support 3.x.

BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=2041

When running with Python 3.x and relying on GenCfgOpt.py to
automatically assign UPD offsets, the script crashed
because some float type variable not compatible with
the operations.
Converted those float variable to int to fix these issues.

Cc: Amy Chan <amy.chan@intel.com>
Cc: Chasel Chiu <chasel.chiu@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Signed-off-by: Ching JenX Cheng <ching.jenx.cheng@intel.com>
Reviewed-by: Chasel Chiu <chasel.chiu@intel.com>