hwmon: (acpi_power_meter) Fix potential memory leak in acpi_power_meter_add()

Although it rarely happens, we should call free_capabilities()
if error happens after read_capabilities() to free allocated strings.

Fixes: de584afa ("hwmon driver for ACPI 4.0 power meters")
Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Link: https://lore.kernel.org/r/20200625043242.31175-1-misono.tomohiro@jp.fujitsu.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/acpi_power_meter.c

@@ -883,7 +883,7 @@ static int acpi_power_meter_add(struct acpi_device *device)
 
 	res = setup_attrs(resource);
 	if (res)
-		goto exit_free;
+		goto exit_free_capability;
 
 	resource->hwmon_dev = hwmon_device_register(&device->dev);
 	if (IS_ERR(resource->hwmon_dev)) {
@@ -896,6 +896,8 @@ static int acpi_power_meter_add(struct acpi_device *device)
 
 exit_remove:
 	remove_attrs(resource);
+exit_free_capability:
+	free_capabilities(resource);
 exit_free:
 	kfree(resource);
 exit: