phy: sun4i: add support for USB phy0

The driver for sun4i USB phys currently supports
only phy1 and phy2 which are used for USB host
controllers. This patch adds support for USB phy0,
which is used by the musb hdrc USB controller.

Signed-off-by: Roman Byshko <rbyshko@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>