dt-bindings: arm: amlogic: Add Meson AXG binding

Introduce new bindings for the Meson AXG SoC which now have
different memory layout.

Signed-off-by: Yixun Lan <yixun.lan@amlogic.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>