ACPI / sleep: Switch to use acpi_dev_get_first_match_dev()

Switch the acpi_pm_finish() to use acpi_dev_get_first_match_dev() instead of
custom approach.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>