ArmPlatformPkg/ArmJunoPkg: use TE 'auto' alignment for SEC modules

ArmPlatformPkg/ArmJunoPkg: use TE 'auto' alignment for SEC modules

No need to hardcode the TE alignment anymore, now that GenFw sets
the PE/COFF alignment according to the alignment requirements of
the ELF input sections.

Also enable FIXED FFS placement so that we can reclaim some of the
space wasted to padding when using clang with 4 KB section alignment.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Tested-by: Leif Lindholm <leif.lindholm@linaro.org>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18195 6f19259b-4bc3-4df7-8a09-765794883524