dt-bindings: arm: amlogic: Add SoC information bindings

Add bindings for the SoC information register of the Amlogic SoCs.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>