We use the IOMMU_TYPE1 of VFIO to realize the subchannels
passthrough, implement a vfio based subchannels passthrough
driver called "vfio-ccw".

Support qemu parameters in the style of:
"-device vfio-ccw,sysfsdev=$mdev_file_path,devno=xx.x.xxxx'
Reviewed-by: NEric Auger <eric.auger@redhat.com>
Acked-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NXiao Feng Ren <renxiaof@linux.vnet.ibm.com>
Signed-off-by: NDong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Message-Id: <20170517004813.58227-8-bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>