docs: driver-api: usb: update dma info

We should not hide the recommend APIs in a obscure place.

Signed-off-by: Randy Li <ayaka@soulik.info>
Link: https://lore.kernel.org/r/20230914172336.18761-3-ayaka@soulik.info


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>