Add the necessary code to create the needed platformdata from devicetree
informations.

The interrupt mode of the chip is not set via devicetree, as it is not
a property of the hardware but instead only a preferred type of operation.
This should probably be made settable via configfs in the future.
The option set as default is the mode the datasheet mentions as default.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>