sunxi: clocks: Add H6 USB clock gates and resets

To enable USB support in U-Boot, add the required clock and reset gates
to the H6 clock driver. Once enabled, the generic EHCI/OCHI drivers will
pick them up from there automatically.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com> # Pine-H64
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>