If 'acpi_device_set_name()' fails, we must free
'acpi_device_bus_id->bus_id' or there is a (potential) memory leak.

Fixes: eb50aaf9 ("ACPI: scan: Use unique number for instance_no")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>