dt-bindings: fsl,fpga-qixis-i2c: add support for LX2160ARDB FPGA

dt-bindings: fsl,fpga-qixis-i2c: add support for LX2160ARDB FPGA

Extend the list of supported compatible strings with fsl,lx2160ardb-fpga.

Since the register map exposed by the LX2160ARDB's FPGA also contains
two GPIO controllers, accept the necessary GPIO pattern property.
At the same time, add the #address-cells and #size-cells properties as
valid ones so that the child nodes of the fsl,lx2160ardb-fpga node are
addressable.

This is necessary because when defining child devices such as the GPIO
controller described in the added example, the child device needs a the
reg property to properly identify its register location in the parent
I2C device address space.

Impose this restriction for the new compatible through an if-statement.

The feature set exposed by these QIXIS FPGA devices is highly dependent
on the board type, meaning that even though the FPGA found on the
LX2160AQDS board (fsl,lx2160aqds-fpga) works in the same way in terms of
access over I2C as the one found on the LX2160ARDB (fsl,lx2160ardb-fpga
added here), the register map inside the device space is different since
there are different on-board devices to be controlled.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>