vfio/ccw: Remove unneeded GFP_DMA

vfio/ccw: Remove unneeded GFP_DMA

Since the ccw_io_region was split out of the private the allocation no
longer needs the GFP_DMA. Remove it.

Reported-by: Christoph Hellwig <hch@infradead.org>
Fixes: c98e16b2fa12 ("s390/cio: Convert ccw_io_region to pointer")
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/1-v4-cea4f5bd2c00+b52-ccw_mdev_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>