drm: Move DRM_MODE_OBJECT_* to uapi headers

These type defines are officially part of the uapi, but ended up in
the wrong headers somehow when we split them all.

Cc: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459347584-30566-3-git-send-email-daniel.vetter@ffwll.ch