iwlwifi: acpi: support device specific method (DSM)

ACPI Device Specific Method (DSM) allows standardized feature
configuration through the ACPI interface without the namespace
pollution of the usual mechanism (ACPI method for each feature).
Add generic function for evaluating DSM objects and function for
evaluating a DSM with no arguments and a single int return value.
also implement the required backport for UUID.

Signed-off-by: Gil Adam <gil.adam@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20200529092401.c3242ff3ba5c.Icb48c8d61bede5dda7ef267bff10e4798e9dc77b@changeid