The rk3399 SoC USB2 PHY is comprised of one Host port and
one OTG port. And OTG port is for USB2.0 part of USB3.0 OTG
controller, as a part to construct a fully feature Type-C
subsystem.

With this patch, we can support OTG port with the following
functions:
- Support BC1.2 charger detect, and use extcon notifier to
  send USB charger types to power driver.
- Support PHY suspend for power management.
- Support OTG Host only mode.
Signed-off-by: William Wu <wulf@rock-chips.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>