Silicon/SynQuacer/Stage2Tables: fix build for cross compile from x86

AArch64 binutils support AArch32 seamlessly when running natively,
which allowed us to drop the -I objcopy argument specifying that
the input format is elf64-little, which is no longer accurate now
that the module can be built in 32-bit mode as well (which makes no
difference whatsoever given that the resulting binary image is only
a set of stage2 page tables)

The same does not apply to binutils hosted on x86, so add back the
appropriate input format depending on the target type.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Leif Lindholm <leif.lindholm@linaro.org>
Tested-by: Leif Lindholm <leif.lindholm@linaro.org>