of: return of_get_cpu_node from of_cpu_device_node_get if CPUs are not registered

Instead of the callsites choosing between of_cpu_device_node_get if the
CPUs are registered as of_node is populated by then and of_get_cpu_node
when the CPUs are not yet registered as CPU of_nodes are not yet stashed
thereby needing to parse the device tree, we can call of_get_cpu_node
in case the CPUs are not yet registered.

This will allow to use of_cpu_device_node_get anywhere hiding the
details from the caller.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>

include/linux/of_device.h

@@ -50,7 +50,7 @@ static inline struct device_node *of_cpu_device_node_get(int cpu)
 	struct device *cpu_dev;
 	cpu_dev = get_cpu_device(cpu);
 	if (!cpu_dev)
-		return NULL;
+		return of_get_cpu_node(cpu, NULL);
 	return of_node_get(cpu_dev->of_node);
 }