fwupdate for arm64

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

Hello all,

I worked with Peter a couple of months ago to get fwupdate working on
arm64 (and with FMP capsules in general). One significant difference
is that fwupdate no longer adds a capsule header if the capsule
already has one, which sounds like an improvement in any case.

These changes are all here

https://github.com/rhboot/fwupdate

but have not turned up in the debian packaged version yet. We will
shortly see more arm64 systems that require these changes, so please
consider pulling them.

Thanks,
Ard.