Revert previous commit; botched testing meant that I missed USB device no
longer attach to the USB 2.0 ports.

Newer versions of U-Boot may disable the USB PHYs and gate their clocks.
Add support for the rk3399 to rkusbphy(4) and implement support for the
required clocks.

ok kevlo@

do actual init of the phy itself when needed.

turn the phy clock on and take the port out of suspend when something
(eg, xhci or ehci) wants to use the port.

before this the code just enabled power on the phy port regulators.

ok kettenis@

add rkusbphy(4), a driver for the usb2phy on rockchip SoCs.

the rkusbphy device has children nodes in the device tree which are
the actual phys. this driver mostly exists to wire those children
up as PHYs and turn the associated regulators on when a host
controller enables the PHYs. in the future it should enable clocks
and take ports out of suspend too.

i'm not enabling this yet because it's useless without some tweaks
in the usb host controller drivers.

ok kettenis@