usbip: Use platform_device_register_full()

The code to create the child platform device is essentially the same as
what platform_device_register_full() does, so change over to use
that same function to reduce duplication.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20231006164312.3528524-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>