s390/cio: return -EFAULT if copy_to_user() fails

Fixes: 120e214e

 ("vfio: ccw: realize VFIO_DEVICE_G(S)ET_IRQ_INFO ioctls")
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>