BaseTools ARM: impose strict alignment only for XIP modules

BaseTools ARM: impose strict alignment only for XIP modules

Given that we only support ARMv7 and up in Tianocore (due to the fact
that the PI spec mandates that the PEI services table pointer be stored
in the TPIDRURW register, which is not available on earlier CPUs), we can
assume that any code executing with the MMU on may perform unaligned
accesses (since the AArch32 bindings in the UEFI spec stipulate that
unaligned accesses should be allowed if supported by the CPU)

So relax the alignment restrictions to XIP modules only, i.e., BASE, SEC,
PEI_CORE and PEIM type modules, exactly like we do for AARCH64 already.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>