wifi: iwlwifi: acpi: cache the DSM functions

wifi: iwlwifi: acpi: cache the DSM functions

Instead of reading the DSM functions on demand, just read them all
when the first DSM function is called and cache the values for all
the other DSM functions. This simplifies the flow.
Since the same will be done for UEFI in the next patch, remove the
ifdef CONFIG_ACPI around the relevant variables.

Once UEFI's cache will be implemented, we'll be able to change
iwl_bios_get_dsm to access the cache directly.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20260111193638.732ff6856796.Iff844bfbb0fea3c3d9654a53254a5b14dbaec8c1@changeid