drm/i915: Reduce clutter by using the local plane pointer

No need to go dig throguh intel_crtc->base.cursor when we already have
the same thing as 'plane' local variable.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -12372,7 +12372,7 @@ intel_check_cursor_plane(struct drm_plane *plane,
 
 finish:
 	if (intel_crtc->active) {
-		if (intel_crtc->base.cursor->state->crtc_w != state->base.crtc_w)
+		if (plane->state->crtc_w != state->base.crtc_w)
 			intel_crtc->atomic.update_wm = true;
 
 		intel_crtc->atomic.fb_bits |=