LinuxKPI; 802.11 initalize ic_vht_cap.supp_mcs

Given the channel struct has an extra bool we cannot assign the
information 1:1 to net80211. While the caps where assigned the
suppoerted mcs sets were not. Fix that.

Sponsored by: The FreeBSD Foundation

(cherry picked from commit ecb2e5f9c30a8c0ae491d07b2300e37eb599c298)