ARM: dts: imx: add Gateworks Ventana GW5600 support

ARM: dts: imx: add Gateworks Ventana GW5600 support

The Gateworks Ventana GW5600 is a media-centric single-board computer based on
the NXP IMX6 SoC with the following features:
 * PoE (emulated 802.3af)
 * IMX6 DualLite Soc (supports IMX6S,IMX6DL,IMX6Q)
 * 1GiB DDR3 DRAM (supports up to 4GiB)
 * 8GB eMMC
 * 1x microSD connector
 * Gateworks System Controller:
  - hardware watchdog
  - hardware monitor
  - pushbutton controller
  - EEPROM storage
  - power control
 * 1x bi-color USER LED
 * 1x front-panel pushbutton
 * 1x front-panel GbE
 * 2x front panel USB 2.0
 * 1x front panel USB OTG
 * 1x SIM socket
 * 1x miniPCIe socket with SATA (mSATA)
 * 1x miniPCIe socket with USB 2.0 (Modem)
 * 1x miniPCIe socket with PCIe, USB 2.0, and SIM
 * RS232/RS485 serial
  - 2x RS232 UARTs (off-board connector)
  - 1x RS485 (loading option)
 * 4x digital I/O signals (PWM/I2C/GPIO/5V/3.3V options)
 * 1x analog input (0 to 5V)
 * 1x CAN (loading option)
 * off-board LVDS:
  - I2C
  - 12V
  - LED driver (4x 330mA strings)
  - matrix keypad controller (8row x 10col)
  - I2S
  - dual-channel LVDS
  - PWM
 * off-board video input:
  - 16bit parallel / MIPI (IPU1_CSI0)
 * GPS (loading option)
 * Analog Video Input (CVBS) 3 inputs (1 active at a time)
 * Analog Audio Input/Output (2ch Line level, optional MIC/HP drivers)
 * HDMI out
 * JTAG programmable
 * Inertial Module

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>