ARM64: simplify cpu_read_bootcpu_ops using OF/DT helper

Once the cpu_logical_map for any logical cpu is populated with the
corresponding physical identifier(i.e. mpidr), it's device node can
be retrieved using the DT helper 'of_get_cpu_node'. Currently the
device tree parsing code to get boot cpu node is duplicated in
'cpu_read_bootcpu_ops'.

This patch replaces the code parsing the device tree for the boot
cpu with of_get_cpu_node.

Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/cpu_ops.c

@@ -78,22 +78,10 @@ int __init cpu_read_ops(struct device_node *dn, int cpu)
 
 void __init cpu_read_bootcpu_ops(void)
 {
-	struct device_node *dn = NULL;
-	u64 mpidr = cpu_logical_map(0);
-
-	while ((dn = of_find_node_by_type(dn, "cpu"))) {
-		u64 hwid;
-		const __be32 *prop;
-
-		prop = of_get_property(dn, "reg", NULL);
-		if (!prop)
-			continue;
-
-		hwid = of_read_number(prop, of_n_addr_cells(dn));
-		if (hwid == mpidr) {
-			cpu_read_ops(dn, 0);
-			of_node_put(dn);
-			return;
-		}
+	struct device_node *dn = of_get_cpu_node(0, NULL);
+	if (!dn) {
+		pr_err("Failed to find device node for boot cpu\n");
+		return;
 	}
+	cpu_read_ops(dn, 0);
 }