LinuxKPI: 802.11: improve cfg80211_chandef_create()

Implement cfg80211_chandef_create() to work with HT. Update enum
with HT channel types. When calling the function from LinuxKPI 802.11
code, pass in NL80211_CHAN_HT20 if HT is supported rather than NO_HT.

Sponsored by: The FreeBSD Foundation
MFC after: 3 days