mac80211: correct ieee80211_iterate_active_interfaces_mtx() locking comments

Commit a05829a7 ("cfg80211: avoid holding the RTNL when calling the
driver") dropped usage of RTNL here and replaced it with
hw->wiphy->mutex. But we didn't update the comments.

Fixes: a05829a7 ("cfg80211: avoid holding the RTNL when calling the driver")
Signed-off-by: Brian Norris <briannorris@chromium.org>
Link: https://lore.kernel.org/r/20210505202829.1039400-1-briannorris@chromium.orgSigned-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -5537,7 +5537,7 @@ void ieee80211_iterate_active_interfaces_atomic(struct ieee80211_hw *hw,
  *
  * This function iterates over the interfaces associated with a given
  * hardware that are currently active and calls the callback for them.
- * This version can only be used while holding the RTNL.
+ * This version can only be used while holding the wiphy mutex.
  *
  * @hw: the hardware struct of which the interfaces should be iterated over
  * @iter_flags: iteration flags, see &enum ieee80211_interface_iteration_flags