phy: sun4i-usb: add support for H6 USB2 PHY

The USB 2.0 PHY on Allwinner H6 SoC is similar to older Allwinner SoCs,
with some USB0 quirk like A83T and PHY index 1/2 missing.

Add support for it.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>