PNP: ide/ide-pnp: Use module_pnp_driver to register driver

Removing some boilerplate by using module_pnp_driver instead of calling
register and unregister in the otherwise empty init/exit functions

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>