wifi: iwlwifi: uefi: open code the parsing of the WGDS table

wifi: iwlwifi: uefi: open code the parsing of the WGDS table

We will soon add support for UNII-9 band in the WGDS table. We need to
decouple the UEFI code from the firmware runtime code.
The firmware runtime is just a software object which will need to grow
and UEFI objects need a new revision to grow. Existing systems will keep
the same UEFI objects.

Just like PPAG and SAR, stop using structures to parse the UEFI tables
since the layout depends on the revision.
The support for the new revision will be added in the next patch, for
now, just do the ground work.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20260319204647.140706e6e91f.I83ca04932bc21aa358119890001e876ced1e1bda@changeid