arm, imx6: add support for aristainetos2 board

add support for imx6dl based aristainetos2 board

U-Boot 2015.04-rc5-00066-g60f6ed4 (Apr 10 2015 - 08:46:27)

CPU:   Freescale i.MX6DL rev1.1 at 792 MHz
Reset cause: WDOG
Board: aristaitenos2
       Watchdog enabled
I2C:   ready
DRAM:  1 GiB
NAND:  1024 MiB
MMC:   FSL_SDHC: 0
SF: Detected N25Q128A with page size 256 Bytes, erase size 64 KiB, total 16 MiB
Display: lg4573 (480x800)
In:    serial
Out:   serial
Err:   serial
Net:   FEC [PRIME]
Hit any key to stop autoboot:  0
=>

Signed-off-by: Heiko Schocher <hs@denx.de>