Use ofnode_ instead of fdt_ APIs so that the drivers can support live DT.
This patch updates usb_get_dr_mode() and usb_get_maximum_speed() to use
ofnode as parameter instead of fdt offset. And all the drivers who use
these APIs update to use live dt APIs at the same time.
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>