platform/chrome: Enable Chrome platforms on 64-bit ARM

With Chrome running on 64-bit ARM devices, add ARM64 to the list of
supported architectures.

Signed-off-by: Thierry Reding <treding@nvidia.com>
[olof; Fixed up due to addition of COMPILE_TEST]
Signed-off-by: Olof Johansson <olof@lixom.net>