usb/max3421: remove the dummy {un,}map_urb_for_dma methods

Now that we have an explicit HCD_DMA flag, there is not need to override
these methods.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20190816062435.881-5-hch@lst.de


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