[DRIVER MODEL] Improved dynamically allocated platform_device interface

Re-jig the simple platform device support to allow private data
to be attached to a platform device, as well as allowing the
parent device to be set.

Example usage:

	pdev = platform_device_alloc("mydev", id);
	if (pdev) {
		err = platform_device_add_resources(pdev, &resources,
						    ARRAY_SIZE(resources));
		if (err == 0)
			err = platform_device_add_data(pdev, &platform_data,
						       sizeof(platform_data));
		if (err == 0)
			err = platform_device_add(pdev);
	} else {
		err = -ENOMEM;
	}
	if (err)
		platform_device_put(pdev);

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>