staging/vboxvideo: don't set dev_priv_size = 0

The compiler already clears this for us.

More important, someone might look what this is actually used for,
and freak out about the dragon staring back at them.
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: Emil Velikov <emil.velikov@collabora.com>
Cc: Fabio Rafael da Rosa <fdr@pid42.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20190204103114.30772-1-daniel.vetter@ffwll.ch

drivers/staging/vboxvideo/vbox_drv.c

@@ -222,7 +222,6 @@ static void vbox_master_drop(struct drm_device *dev, struct drm_file *file_priv)
 static struct drm_driver driver = {
 	.driver_features =
 	    DRIVER_MODESET | DRIVER_GEM | DRIVER_PRIME | DRIVER_ATOMIC,
-	.dev_priv_size = 0,
 
 	.lastclose = drm_fb_helper_lastclose,
 	.master_set = vbox_master_set,