There are no users of X86_DEV_DMA_OPS left, so remove the code.

Link: https://lore.kernel.org/r/1579613871-301529-8-git-send-email-jonathan.derrick@intel.comSigned-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jon Derrick <jonathan.derrick@intel.com>