BaseTools/GenFv: Account for rebase of FV section containing VTF file

BaseTools/GenFv: Account for rebase of FV section containing VTF file

Account for rebase of FV section containing VTF file on IA32/IA64.
This supports cases where the reset vector may not be set at 0xFFFFFFF0.

For example, FV section defined as:
[FV.FvSecPei]
  FvBaseAddress = $(FV_BOOT_BASE)
  FvForceRebase = TRUE

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Leo Duran <leo.duran@amd.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>