arm64: dts: lx2160a-rdb: describe the QIXIS FPGA and two child GPIO controllers

arm64: dts: lx2160a-rdb: describe the QIXIS FPGA and two child GPIO controllers

Describe the FPGA present on the LX2160ARDB board as a simple-mfd I2C
device. The FPGA presents registers that deal with power-on-reset
timing, muxing, SFP cage monitoring and control etc.

Also add the two GPIO controllers responsible for monitoring and
controlling the SFP+ cages used for MAC5 and MAC6.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>