sunxi: musb: Power off OTG port VBUS when disabled

The Linux kernel musb driver expects VBUS to be off while initializing
musb. Having it on results in a repeating string of warnings, followed
by an unusable peripheral. The peripheral is only usable after
physically removing the OTG adapter, letting musb reset its state.

This partially reverts commit c9f8947e ("sunxi: usb-phy: Never
power off the usb ports")

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>