arm64: allwinner: a64: enable USB host controller for BPi M64

Banana Pi M64 connects the USB host-only controller on A64 SoC to a USB
hub, which provided the two USB Type-A ports on the board.

Enable the USB host controller.

The OTG function of the Micro-USB port needs the drivevbus function of
the AXP803 driver implemented, so it's not enabled now.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>