imx6: geam6ul: Add NAND support

imx6: geam6ul: Add NAND support

Add NAND support for Engicam GEAM6UL board.

Boot Log:
--------
U-Boot SPL 2016.11-g537fa5f (Nov 28 2016 - 11:42:28)
Trying to boot from NAND
NAND : 256 MiB

U-Boot 2016.11-g537fa5f (Nov 28 2016 - 11:20:06 +0100)

CPU:   Freescale i.MX6UL rev1.1 69 MHz (running at 396 MHz)
CPU:   Automotive temperature grade (-40C to 125C) at 42C
Reset cause: WDOG
Model: Engicam GEAM6UL
DRAM:  128 MiB
NAND:  256 MiB
MMC:   FSL_SDHC: 0
* Warning - bad CRC, using default environment

In:    serial
Out:   serial
Err:   serial
Net:   No ethernet found.
Hit any key to stop autoboot:  0

Cc: Stefano Babic <sbabic@denx.de>
Cc: Matteo Lisi <matteo.lisi@engicam.com>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>