imx: Add PHYTEC phyBOARD-i.MX6UL-Segin

Port for the PHYTEC phyBOARD-i.MX6UL-Segin single board computer. Based on
the PHYTEC phyCORE-i.MX6UL SOM (PCL063).

CPU:   Freescale i.MX6UL rev1.2 528 MHz (running at 396 MHz)
CPU:   Industrial temperature grade (-40C to 105C) at 44C
Reset cause: POR
Board: PHYTEC phyCORE-i.MX6UL
I2C:   ready
DRAM:  256 MiB
NAND:  512 MiB
MMC:   FSL_SDHC: 0
In:    serial
Out:   serial
Err:   serial
Net:   FEC0

Working:
 - Eth0
 - i2C
 - MMC/SD
 - NAND
 - UART (1 & 5)
 - USB (host & otg)

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>