iwlwifi: mvm: refactor ACPI DSM evaluation function

Instead of implementing the DSM evaluation function in the MVM code,
refactor it so it can be generalized and part of the common ACPI
implementation.

Signed-off-by: Harish Mitty <harish.mitty@intel.com>
[reworded subject and commit message]
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210331121101.a24af3551aac.I8e6bd5eb05f853b6331fa4823750f7ba8ffe46e6@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>