Interop problem with Quantum Fiber WiFi7 pods (duplicate RSNXE IE)

[Vivek Das Mohapatra <vivek@collabora.com>]

Hi - we've had reports of an incompatibility between network manager and
the wifi7 hardware mentioned when using iwd as the backend.

 From what we've been able to tell:

validate_mgmt_ies() fails
cause: disallowed duplicate IEs in the AssocResponse frame

We appear to have two dupes:

221 - IE_TYPE_VENDOR_SPECIFIC - allowed
244 - IE_TYPE_RSNX - not allowed as a dup.

We checked IEEE 80211-2020.pdf couldn't find specific details about IEs
that can be duplicated vs the ones that can’t.
[ Sections 9.4.2.1 and 9.4.2.241 ]

We've tried various devices and software combinations (linux and non)
and it seems to be an interop problem with iwd specifically - we think 
adding IE_TYPE_RSNX to the allowed dups list in validate_mgmt_ies should
do the trick.

To summarise:

  - nm + iwd (v2.14) cannot auth against a Quantum Fiber WiFi7 pod
  - there's a duplicate IE in the assocresponse which iwd is rejecting
  - we think that IE should be allowed as a dup
  - nm + wpa_supplicant seems to work
  - we tried some non-linux device and they were also able to auth

Does that sound like a reasonable fix? Do you want a patch?