Because some platforms may required to disable some flags, this
allow to control which flags are passed for each platform.

This will display all flags passed during the build allowing to
make debugging easier.

Signed-off-by: Wei Gao <gaw1lud@bosch.com>

Signed-off-by: Dylan Aïssi <dylan.aissi@collabora.com>

Signed-off-by: Dylan Aïssi <dylan.aissi@collabora.com>

At the moment we are only building for a single arm64 target, so mark
this as arm64 only (we may in the future build for arm32 as well, but
we're not at the moment). Also we'll produce a single package of
binaries for all supported boards. This package is used as a build time
dependency of U-Boot rather than being installed directly on a target.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>