In preparation to convert board-level bindings to json-schema, move
various misc SoC bindings out to their own file.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Jun Nie <jun.nie@linaro.org>
Cc: Baoyou Xie <baoyou.xie@linaro.org>
Cc: devicetree@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Acked-by: NShawn Guo <shawnguo@kernel.org>
Signed-off-by: NRob Herring <robh@kernel.org>

Add device tree support for ZX296718 SoC and evaluation board based
on it.  Also document new values.
Signed-off-by: NJun Nie <jun.nie@linaro.org>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

Add initial dts file and document for ZX296702 and board ZX296702-AD1.
More peripherals will be added later.
Signed-off-by: NJun Nie <jun.nie@linaro.org>
Signed-off-by: NKevin Hilman <khilman@linaro.org>