ACPI: NFIT: Import GUID before use

Strictly speaking the comparison between guid_t and raw buffer
is not correct. Import GUID to variable of guid_t type and then
compare.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20211213204632.56735-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>