cpuidle: riscv-sbi: Use scoped device node handling to fix missing of_node_put

Two return statements in sbi_cpuidle_dt_init_states() did not drop the
OF node reference count.  Solve the issue and simplify entire error
handling with scoped/cleanup.h.

Fixes: 6abf32f ("cpuidle: Add RISC-V SBI CPU idle driver")
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://patch.msgid.link/20240820094023.61155-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: krzk

drivers/cpuidle/cpuidle-riscv-sbi.c

@@ -8,6 +8,7 @@
 
 #define pr_fmt(fmt) "cpuidle-riscv-sbi: " fmt
 
+#include <linux/cleanup.h>
 #include <linux/cpuhotplug.h>
 #include <linux/cpuidle.h>
 #include <linux/cpumask.h>
@@ -236,19 +237,16 @@ static int sbi_cpuidle_dt_init_states(struct device *dev,
 {
 	struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu);
 	struct device_node *state_node;
-	struct device_node *cpu_node;
 	u32 *states;
 	int i, ret;
 
-	cpu_node = of_cpu_device_node_get(cpu);
+	struct device_node *cpu_node __free(device_node) = of_cpu_device_node_get(cpu);
 	if (!cpu_node)
 		return -ENODEV;
 
 	states = devm_kcalloc(dev, state_count, sizeof(*states), GFP_KERNEL);
-	if (!states) {
-		ret = -ENOMEM;
-		goto fail;
-	}
+	if (!states)
+		return -ENOMEM;
 
 	/* Parse SBI specific details from state DT nodes */
 	for (i = 1; i < state_count; i++) {
@@ -264,10 +262,8 @@ static int sbi_cpuidle_dt_init_states(struct device *dev,
 
 		pr_debug("sbi-state %#x index %d\n", states[i], i);
 	}
-	if (i != state_count) {
-		ret = -ENODEV;
-		goto fail;
-	}
+	if (i != state_count)
+		return -ENODEV;
 
 	/* Initialize optional data, used for the hierarchical topology. */
 	ret = sbi_dt_cpu_init_topology(drv, data, state_count, cpu);
@@ -277,10 +273,7 @@ static int sbi_cpuidle_dt_init_states(struct device *dev,
 	/* Store states in the per-cpu struct. */
 	data->states = states;
 
-fail:
-	of_node_put(cpu_node);
-
-	return ret;
+	return 0;
 }
 
 static void sbi_cpuidle_deinit_cpu(int cpu)