drm/vmwgfx: Stop consulting plane->fb

We want to get rid of plane->fb on atomic drivers. Stop looking at it.

Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
Cc: Sinclair Yeh <syeh@vmware.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180322152313.6561-13-ville.syrjala@linux.intel.com
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

drivers/gpu/drm/vmwgfx/vmwgfx_kms.c

@@ -385,9 +385,9 @@ vmw_du_cursor_plane_atomic_update(struct drm_plane *plane,
 	hotspot_x = du->hotspot_x;
 	hotspot_y = du->hotspot_y;
 
-	if (plane->fb) {
-		hotspot_x += plane->fb->hot_x;
-		hotspot_y += plane->fb->hot_y;
+	if (plane->state->fb) {
+		hotspot_x += plane->state->fb->hot_x;
+		hotspot_y += plane->state->fb->hot_y;
 	}
 
 	du->cursor_surface = vps->surf;