sna: Remember to decouple the fb on closing

... so that we actually attach a new one after regen!

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

src/sna/sna_display.c

@@ -1846,4 +1846,3 @@ sna_wait_for_scanline(struct sna *sna, PixmapPtr pixmap,
 	kgem_advance_batch(&sna->kgem, 5);
 	return true;
 }
-

src/sna/sna_driver.c

@@ -763,6 +763,7 @@ static Bool sna_close_screen(int scrnIndex, ScreenPtr screen)
 		sna->directRenderingOpen = FALSE;
 	}
 
+	sna_mode_remove_fb(sna);
 	xf86GARTCloseScreen(scrnIndex);
 
 	scrn->vtSema = FALSE;