x86: Update the comment about booting for FSP2

The comment here applies only to FSP1, so update it.
Signed-off-by: NSimon Glass <sjg@chromium.org>
Reviewed-by: NBin Meng <bmeng.cn@gmail.com>
Reviewed-by: NWolfgang Wallner <wolfgang.wallner@br-automation.com>

arch/x86/cpu/start.S

@@ -124,6 +124,7 @@ car_init_ret:
 #endif
 #else
 	/*
+	 * Instructions for FSP1, but not FSP2:
 	 * U-Boot enters here twice. For the first time it comes from
 	 * car_init_done() with esp points to a temporary stack and esi
 	 * set to zero. For the second time it comes from fsp_init_done()