mac80211: fix return value of ieee80211_chandef_he_6ghz_oper

ieee80211_chandef_he_6ghz_oper() needs to return true if it
determined a value 6 GHz chandef, fix that.

Fixes: 1d00ce80 ("mac80211: support S1G association")
Signed-off-by: Wen Gong <wgong@codeaurora.org>
Link: https://lore.kernel.org/r/1606121152-3452-1-git-send-email-wgong@codeaurora.org


[rewrite commit message]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>