net80211: add VHT5G and VHT2G checks/return to media_status

Add the fields for VHT (2Ghz and 5Ghz) to report back by media_status
so we actually have a chance to get the right information.

Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Reviewed by: adrian
Differential Revision: https://reviews.freebsd.org/D35977