ACPI: glue: Rearrange acpi_device_notify()

Make the code flow in acpi_device_notify() more straightforward and
make it use dev_dbg() and acpi_handle_debug() for printing debug
messages.

The only expected functional impact of this change is the content of
the debug messages printed by acpi_device_notify().

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