ARM: dts: imx: add Gateworks Ventana GW5904 support

ARM: dts: imx: add Gateworks Ventana GW5904 support

The Gateworks Ventana GW5904 is a single-board computer based on the NXP
IMX6 SoC with the following features:
 * IMX6 DualLite Soc (supports IMX6S,IMX6DL,IMX6Q)
 * 2048MB DDR3 DRAM (4x64bit) (options up to 4GiB)
 * 8GB eMMC
 * Gateworks System Controller:
  - hardware watchdog
  - hardware monitor
  - pushbutton controller
  - EEPROM storage
  - power control
 * JTAG programmable
 * 1x miniPCIe socket (with PCIe, USB)
 * 1x miniPCIe socket (USB)
 * 1x M.2 socket (USB, 2x SIM)
 * Inertial Module (LSM9DS1 9DOF: 3x acc, 3x rate, 3x mag)
 * GPS (optional uBlox EVA-M8M)
 * Application headers:
  - 2x RS232 UART (TX/RX/CTS/RTS)
  - 8x TTL GPIO (3x configurable as PWM)
  - 1x LVDS display 3D+C with i2c touch and PWM backlight
 * MV88E6176 GbE Switch (uplink to IMX FEC)
 * Front panel connectors:
  - 1x user programmable LED
  - 1x configurable user pushbutton
  - 1x USB OTG
  - 4x GbE LAN

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