ARM: dts: imx6ul: add support for Ka-Ro electronics TXUL modules

ARM: dts: imx6ul: add support for Ka-Ro electronics TXUL modules

The TXUL-0010/-0011 modules are Computers On Module manufactured by
  Ka-Ro electronics GmbH with the following characteristics:
  Processor    Freescale i.MX 6UltraLite MCIMX6G2, 528 MHz
  RAM          256MB 16-bit DDR3 SDRAM
  ROM          128MB NAND Flash (TXUL-0010) / 4GB eMMC (TXUL-0011)
  Power supply Single 3.3 to 5V
  Size         26mm SO-DIMM
  Temp. Range  -40°C to 85°C

Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>