[U-Boot] [PATCH 2/9] Makefile: use "arm64" architecture for U-Boot image files

[Philipp Tomsich]

> On 21.02.2019, at 02:30, Andre Przywara <andre.przywara at arm.com> wrote:
> 
> At the moment we use the arch/arm directory for arm64 boards as well,
> so the Makefile will pick up the "arm" name for the architecture to use
> for tagging binaries in U-Boot image files.
> Differentiate between the two by looking at the CPU variable being defined
> to "armv8", and use the arm64 architecture name on creating the image
> file if that matches.
> 
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>

Reviewed-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>