memory: ti-aemif: add bindings for AEMIF driver

Add bindings for TI Async External Memory Interface (AEMIF) controller.

The Async External Memory Interface (EMIF16/AEMIF) controller is intended to
provide a glue-less interface to a variety of asynchronous memory devices like
ASRA M, NOR and NAND memory. A total of 256M bytes of any of these memories
can be accessed via 4 chip selects with 64M byte access per chip select.

We are not encoding CS number in reg property, it's memory partition number.
The CS number is encoded for Davinci NAND node using standalone property
"ti,davinci-chipselect" and we need to provide two memory ranges to it,
as result we can't encode CS number in "reg" for AEMIF child devices
(NAND/NOR/etc), as it will break bindings compatibility.

In this patch, NAND node is used just as an example of child node.

Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>