usb: gadget: Use correct APIs and data types for UUID handling

We have two types for UUIDs depending on the byte ordering.
Instead of explaining how bytes should go over the wire,
use dedicated APIs and data types. This removes a confusion
over the byte ordering.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-By: Jó Ágila Bitsch <jgilab@gmail.com>
Link: https://lore.kernel.org/r/20230125143425.85268-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>