net80211: improve error handling from ieee80211_parse_beacon()

Following up on fb8c87b4f3bfdfac014f9d894fe75fbad0391b24, which was
supposed to go into all supported branches, increase ieee80211_scanparams
status field from 8bit to 32bit (enum size) and add a dedicated error
code for Mesh ID.

Sponsored by: The FreeBSD Foundation

(cherry picked from commit 7354782698f1cf5d6b368a9b1e65cfe3ee7f235c)