ARM: mmp: add usb device support for ttc dkb

There is an U2O OTG controller on ttc dkb, this patch is going to enable
it.
At this moment, it can only works in device mode, because when works in
host mode, it needs to supply vbus, but we have no vbus driver added
at this moment. Once the vbus driver is added, I'll prepar another
patch to enable the switch function.

Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com>