ot1200: add support for EHCI

ot1200: add support for EHCI

U-Boot 2014.10-17457-g0b23780-dirty (Nov 10 2014 - 11:41:04)

CPU:   Freescale i.MX6D rev1.2 at 792 MHz
Reset cause: WDOG
Board: ot1200
I2C:   ready
DRAM:  1 GiB
MMC:   FSL_SDHC: 0, FSL_SDHC: 1
SF: Detected M25P16 with page size 256 Bytes, erase size 64 KiB, total 2 MiB
In:    serial
Out:   serial
Err:   serial
Net:   using phy at 0
FEC [PRIME]
Hit any key to stop autoboot:  0
=> usb start
(Re)start USB...
USB0:   Port not available.
USB1:   USB EHCI 1.00
scanning bus 1 for devices... 4 USB Device(s) found
=> usb tree
USB device tree:
  1  Hub (480 Mb/s, 0mA)
  |  u-boot EHCI Host Controller
  |
  +-2  Hub (480 Mb/s, 2mA)
    |
    +-3  Mass Storage (480 Mb/s, 80mA)
    |    USBest Technology USB Mass Storage Device 0000000000028B
    |
    +-4  Vendor specific (480 Mb/s, 2mA)

=>

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>