Introduce a new ioctl, DRM_IOCTL_SET_VERSION. This ioctl allows the server
or client to notify the DRM that it expects a certain version of the device
dependent or device independent interface. If the major doesn't match or minor
is too large, EINVAL is returned. A major of -1 means that the requestor
doesn't care about that portion of the interface. The ioctl returns the actual
versions in the same struct.