dt-bindings: arm: amlogic: add A1 bindings

Add bindings for the new Amlogic A1 SoC family.

A1 is an application processor designed for smart audio and IoT applications,
with dual core Cortex-A35.

Signed-off-by: Jianxin Pan <jianxin.pan@amlogic.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>