UBUNTU: SAUCE: i915_bpo: Silence the warning about watermark entries not changing

BugLink: http://bugs.launchpad.net/bugs/1580272

This will have to do for v4.4, backporting everything from v4.8.6 is just
not feasible.
Signed-off-by: Timo Aaltonen <timo.aaltonen@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

ubuntu/i915/intel_pm.c

@@ -3672,7 +3672,7 @@ static void skl_update_other_pipe_wm(struct drm_device *dev,
 		 * because it was really needed, so we expect the WM values to
 		 * be different.
 		 */
-		WARN_ON(!wm_changed);
+//		WARN_ON(!wm_changed);
 
 		skl_compute_wm_results(dev, &pipe_wm, r, intel_crtc);
 		r->dirty[intel_crtc->pipe] = true;