drm/i915/skl: Store the new WM state at the very end of the update

We're going to add a new step, let's not hide the copy of the new WM
state inside one inner function, but as a 1st level operation in the WM
update.

v2: Split the staging results structure to not exceed the 1Kb stack
    allocation in skl_update_wm()

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_pm.c

@@ -3463,8 +3463,6 @@ static void skl_write_wm_values(struct drm_i915_private *dev_priv,
 				   new->ddb.cursor[pipe].start);
 		}
 	}
-
-	dev_priv->wm.skl_hw = *new;
 }
 
 static bool skl_update_pipe_wm(struct drm_crtc *crtc,
@@ -3558,6 +3556,9 @@ static void skl_update_wm(struct drm_crtc *crtc)
 
 	skl_update_other_pipe_wm(dev, crtc, &config, results);
 	skl_write_wm_values(dev_priv, results);
+
+	/* store the new configuration */
+	dev_priv->wm.skl_hw = *results;
 }
 
 static void