drm/vmwgfx: Work around drm removal of control nodes

vmware tools has a daemon that gets layout information from the GUI and
forwards it to DRM so that the modesetting code can set preferred connector
locations and modes. This daemon was using control nodes but since control
nodes were just removed, make it possible for the daemon to use render- or
primary nodes instead. This is a bit ugly but will allow drm to proceed with
removal of the mostly unused control-node code and allow vmware to proceed
with fixing up automatic layout settings for gnome-shell/wayland.

We bump minor to inform user-space about the api change.

Cc: <stable@vger.kernel.org>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170221104227.2854-1-thellstrom@vmware.com