drm: Drop unused forward declaration of drm_version

Signed-off-by: Gabriel Krisman Bertazi <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Link: http://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/drm_ioctl.c

···
  * broken.
  */
 
-static int drm_version(struct drm_device *dev, void *data,
-		       struct drm_file *file_priv);
-
 /*
  * Get the bus id.
  *