There is export_uuid() function which exports uuid_t to the u8 array.
Use it instead of open coding variant.

This allows to hide the uuid_t internals.
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>