mac80211: do not disable HE if HT is missing on 2.4 GHz

mac80211: do not disable HE if HT is missing on 2.4 GHz

VHT is not supported on 2.4 GHz, but HE is; don't disable HE if HT
is missing there, do that only on 5 GHz (6 GHz is only HE).

Fixes: ed77152889fced1 ("mac80211: determine chandef from HE 6 GHz operation")
Signed-off-by: Wen Gong <wgong@codeaurora.org>
Link: https://lore.kernel.org/r/010101747cb617f2-593c5410-1648-4a42-97a0-f3646a5a6dd1-000000@us-west-2.amazonses.com
[rewrite the commit message]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>