phy: sun4i-usb: add Allwinner F1C100s support

The Allwinner F1C100s implements a single USB PHY, connected to its MUSB
OTG controller. The USB PHY is of the simpler, older type (like the A10),
the only real difference is that it's indeed only one PHY.

Add a struct describing those F1C100s USB PHY properties, and connect it
to the new compatible string.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>