[wlan][sme] Add rsn capabilities to softAP

This resolves an issue where vendor drivers might add a 0 cap byte
and break secure associations due to a mismatch in our EAPOL msg 3.

Test: Manual
Fixes: 120733

Change-Id: Iec6983329809ee0239e6016a9d8ea79e9c5688d1
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/796483
Commit-Queue: Dylan Swiggett <swiggett@google.com>
Reviewed-by: Karthik Krishnaswami <karthikrish@google.com>