wifi: cfg80211: fix kernel-doc for wiphy_delayed_work_flush()

Clearly, there's no space in the function name, not sure how
that could've happened. Put the underscore that it should be.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 56cfb8ce ("wifi: cfg80211: add flush functions for wiphy work")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -5929,7 +5929,7 @@ void wiphy_delayed_work_cancel(struct wiphy *wiphy,
 			       struct wiphy_delayed_work *dwork);
 
 /**
- * wiphy_delayed work_flush - flush previously queued delayed work
+ * wiphy_delayed_work_flush - flush previously queued delayed work
  * @wiphy: the wiphy, for debug purposes
  * @work: the work to flush
  *