binman: Fix FIT image overlap issues for testFitSplitElf

binman: Fix FIT image overlap issues for testFitSplitElf

Fix one binman test that has memory region overlap issue, the test case
needed to be updated to use non-overlapping memory layouts.

* Tests fixed:
  - testFitSplitElf

* Changes made:
  1. ELF section layouts: added elf_sections_tee.lds with different
     address for TEE to avoid overlap with ATF address defined in
     elf_sections.lds
  2. Makefile to properly build elf_sections_tee binary
  3. Updat ftest.py to use separate ELF files for TEE vs ATF components
     in split-elf operations.

An upcoming commit will validate if the memory region is overlapped

Signed-off-by: Aristo Chen <aristo.chen@canonical.com>