feat(allwinner): provide CPU idle states to the rich OS

When using SCPI as the PSCI backend, firmware can wake up the CPUs and
cluster from sleep, so CPU idle states are available for the rich OS to
use. In that case, advertise them to the rich OS via the DTB.

Change-Id: I718ef6ef41212fe5213b11b4799613adbbe6e0eb
Signed-off-by: Samuel Holland <samuel@sholland.org>
diff --git a/plat/allwinner/sun50i_h6/sunxi_idle_states.c b/plat/allwinner/sun50i_h6/sunxi_idle_states.c
new file mode 100644
index 0000000..4339bcd
--- /dev/null
+++ b/plat/allwinner/sun50i_h6/sunxi_idle_states.c
@@ -0,0 +1,11 @@
+/*
+ * Copyright (c) 2022, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <sunxi_private.h>
+
+const struct psci_cpu_idle_state sunxi_idle_states[] = {
+	{}
+};