drm/vmwgfx: Add suggested screen x and y connector properties

Introduced by qxl, add these properties as a generic way to tell a
display manager about the GUI layout.

Also add the hotplug_mode_update_property which advises display managers to
reread the mode list on a hotplug event.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>

drivers/gpu/drm/vmwgfx/vmwgfx_drv.h

@@ -408,6 +408,7 @@ struct vmw_private {
 	enum vmw_display_unit_type active_display_unit;
 	struct vmw_legacy_display *ldu_priv;
 	struct vmw_overlay *overlay_priv;
+	struct drm_property *hotplug_mode_update_property;
 	unsigned num_implicit;
 	struct vmw_framebuffer *implicit_fb;