phy: rockchip: inno-usb2: Add support #address_cells = 2

New Rockchip devices have the usb phy nodes as standalone devices.
These nodes have register nodes with #address_cells = 2, but only
use 32 bit addresses.

Adjust the driver to check if the returned address is "0", and adjust
the index in that case.

Derived and adjusted the similar change from linux-next with below
 commit <9c19c531dc98> ("phy: phy-rockchip-inno-usb2: support
 #address_cells = 2")

Co-developed-by: Manoj Sai <abbaraju.manojsai@amarulasolutions.com>
Signed-off-by: Manoj Sai <abbaraju.manojsai@amarulasolutions.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>