ACPI: bus: Rename functions to avoid name collision

There is a name collision between acpi_device_notify() defined in
bus.c and another static function defined in glue.c.

Since the latter is going to be exported from that file, rename the
former to acpi_notify_device() and rename acpi_device_notify_fixed()
to follow the same naming pattern.

No functional impact.

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