cacheinfo: Use of_cpu_device_node_get instead cpu_dev->of_node

The of_cpu_device_node_get takes care of fetching the CPU'd device node
either from cached cpu_dev->of_node if cpu_dev is initialised or uses
of_get_cpu_node to parse and fetch node if cpu_dev isn't available yet.

Just use of_cpu_device_node_get instead of getting the cpu device first
and then using cpu_dev->of_node for two reasons:
1. There is no other use of cpu_dev and can be simplified
2. It enabled the use detect_cache_attributes and hence cache_setup_of_node
   much earlier before the CPUs are registered as devices.

Link: https://lore.kernel.org/r/20220704101605.1318280-3-sudeep.holla@arm.com
Tested-by: Ionela Voinescu <ionela.voinescu@arm.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/base/cacheinfo.c

@@ -14,7 +14,7 @@
 #include <linux/cpu.h>
 #include <linux/device.h>
 #include <linux/init.h>
-#include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/smp.h>
@@ -157,7 +157,6 @@ static int cache_setup_of_node(unsigned int cpu)
 {
 	struct device_node *np;
 	struct cacheinfo *this_leaf;
-	struct device *cpu_dev = get_cpu_device(cpu);
 	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
 	unsigned int index = 0;
 
@@ -166,11 +165,7 @@ static int cache_setup_of_node(unsigned int cpu)
 		return 0;
 	}
 
-	if (!cpu_dev) {
-		pr_err("No cpu device for CPU %d\n", cpu);
-		return -ENODEV;
-	}
-	np = cpu_dev->of_node;
+	np = of_cpu_device_node_get(cpu);
 	if (!np) {
 		pr_err("Failed to find cpu%d device node\n", cpu);
 		return -ENOENT;