usb-storage: use hcd_uses_dma to check for DMA capabilities

The dma_mask on its own doesn't mean much.  Instead check for the actual
flag.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20190903084615.19161-4-hch@lst.de


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