phy: rockchip: usbdp: Find phy-id from the io address

The upstream Linux kernel driver find the phy-id from the io address.

Change to use a similar method as the U-Boot inno-usb2 phy driver and
the Linux kernel driver to set correct phy-id.

This is based on the linux-phy next commit 2f70bbddeb45 ("phy: rockchip:
add usbdp combo phy driver").

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>