Add support to export a /cpus node to the device tree.

This patch creates and populates the /cpus node in a device tree
based on the existing topology. It uses the minimum required nodes
and properties to satisfy the binding as specified in
https://www.kernel.org/doc/Documentation/devicetree/bindings/arm/cpus.txt

Signed-off-by: Javier Almansa Sobrino <javier.almansasobrino@arm.com>
Change-Id: I03bf4e9a6427da0a3b8ed013f93d7bc43b5c4df0
diff --git a/include/common/fdt_fixup.h b/include/common/fdt_fixup.h
index 0248de9..29d8b3a 100644
--- a/include/common/fdt_fixup.h
+++ b/include/common/fdt_fixup.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2019-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -11,5 +11,7 @@
 int dt_add_psci_cpu_enable_methods(void *fdt);
 int fdt_add_reserved_memory(void *dtb, const char *node_name,
 			    uintptr_t base, size_t size);
+int fdt_add_cpus_node(void *dtb, unsigned int afflv0,
+		      unsigned int afflv1, unsigned int afflv2);
 
 #endif /* FDT_FIXUP_H */