nl80211: Fix compilation

Commit 7ea3e110 seems to have
introduced:

net/wireless/nl80211.c: In function ‘nl80211_get_station’:
net/wireless/nl80211.c:4802:34: error: incompatible type for argument 1 of ‘cfg80211_sinfo_release_content’
   cfg80211_sinfo_release_content(sinfo);
                                  ^~~~~
In file included from net/wireless/nl80211.c:24:0:
./include/net/cfg80211.h:5721:20: note: expected ‘struct station_info *’ but argument is of type ‘struct station_info’
 static inline void cfg80211_sinfo_release_content(struct station_info *sinfo)
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fixes: 7ea3e110 ("cfg80211: release station info tidstats where needed")
Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>