wireless: FTM: fix kernel-doc "cannot understand" warnings

Fix kernel-doc warnings in FTM due to missing "struct" keyword.

Fixes 109 warnings from <net/cfg80211.h>:
../include/net/cfg80211.h:2838: warning: cannot understand function prototype: 'struct cfg80211_ftm_responder_stats '

and fixes 88 warnings from <net/mac80211.h>:
../include/net/mac80211.h:477: warning: cannot understand function prototype: 'struct ieee80211_ftm_responder_params '

Fixes: 81e54d08d9 ("cfg80211: support FTM responder configuration/statistics")
Fixes: bc847970f4 ("mac80211: support FTM responder configuration/statistics")

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Pradeep Kumar Chitrapu <pradeepc@codeaurora.org>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: David Spinadel <david.spinadel@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -2823,7 +2823,7 @@ struct cfg80211_external_auth_params {
 };
 
 /**
- * cfg80211_ftm_responder_stats - FTM responder statistics
+ * struct cfg80211_ftm_responder_stats - FTM responder statistics
  *
  * @filled: bitflag of flags using the bits of &enum nl80211_ftm_stats to
  *	indicate the relevant values in this struct for them

include/net/mac80211.h

@@ -467,7 +467,7 @@ struct ieee80211_mu_group_data {
 };
 
 /**
- * ieee80211_ftm_responder_params - FTM responder parameters
+ * struct ieee80211_ftm_responder_params - FTM responder parameters
  *
  * @lci: LCI subelement content
  * @civicloc: CIVIC location subelement content