Replace DRM_IOCTL_ARGS with (dev, data, file_priv) and remove DRM_DEVICE.

The data is now in kernel space, copied in/out as appropriate according to the
This results in DRM_COPY_{TO,FROM}_USER going away, and error paths to deal
with those failures.  This also means that XFree86 4.2.0 support for i810 DRM
is lost.