phy-sun4i-usb: Add support for boards with broken Vusb-detection

On some boards we cannot detect the presence of an external Vusb, because
e.g. the 5V of the otg connector is directly connected to the 5V of the board,
and thus is always high.

This commit adds support for using such boards by only looking at the
id-detection pin.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>