wifi: mac80211: Fix 6 GHz Band capabilities element advertisement in lower bands

wifi: mac80211: Fix 6 GHz Band capabilities element advertisement in lower bands

Currently, when adding the 6 GHz Band Capabilities element, the channel
list of the wiphy is checked to determine if 6 GHz is supported for a given
virtual interface. However, in a multi-radio wiphy (e.g., one that has
both lower bands and 6 GHz combined), the wiphy advertises support for
all bands. As a result, the 6 GHz Band Capabilities element is incorrectly
included in mesh beacon and station's association request frames of
interfaces operating in lower bands, without verifying whether the
interface is actually operating in a 6 GHz channel.

Fix this by verifying if the interface operates on 6 GHz channel
before adding the element. Note that this check cannot be placed
directly in ieee80211_put_he_6ghz_cap() as the same function is used to
add probe request elements while initiating scan in which case the
interface may not be operating in any band's channel.

Signed-off-by: Ramya Gnanasekar <ramya.gnanasekar@oss.qualcomm.com>
Signed-off-by: Rameshkumar Sundaram <rameshkumar.sundaram@oss.qualcomm.com>
Link: https://patch.msgid.link/20250606104436.326654-1-rameshkumar.sundaram@oss.qualcomm.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>