wifi: mac80211: add netdev per-link debugfs data and driver hook

wifi: mac80211: add netdev per-link debugfs data and driver hook

This adds the infrastructure to have netdev specific per-link data both
for mac80211 and the driver in debugfs. For the driver, a new callback
is added which is only used if MLO is supported.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230301115906.fb4c947e4df8.I69b3516ddf4c8a7501b395f652d6063444ecad63@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>