ACPI / glue: Add acpi_platform_notify() function

Instead of relying on the "platform_notify" callback hook,
introducing separate notification function
acpi_platform_notify() and calling that directly from
drivers core when device entries are added and removed.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>