nl80211: fix NL80211_ATTR_FTM_RESPONDER policy

The nested policy here should be established using the
NLA_POLICY_NESTED() macro so the length is properly
filled in.

Cc: stable@vger.kernel.org
Fixes: 81e54d08 ("cfg80211: support FTM responder configuration/statistics")
Link: https://lore.kernel.org/r/20200412004029.9d0722bb56c8.Ie690bfcc4a1a61ff8d8ca7e475d59fcaa52fb2da@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -644,10 +644,8 @@ const struct nla_policy nl80211_policy[NUM_NL80211_ATTR] = {
 	[NL80211_ATTR_HE_CAPABILITY] = { .type = NLA_BINARY,
 					 .len = NL80211_HE_MAX_CAPABILITY_LEN },
 
-	[NL80211_ATTR_FTM_RESPONDER] = {
-		.type = NLA_NESTED,
-		.validation_data = nl80211_ftm_responder_policy,
-	},
+	[NL80211_ATTR_FTM_RESPONDER] =
+		NLA_POLICY_NESTED(nl80211_ftm_responder_policy),
 	[NL80211_ATTR_TIMEOUT] = NLA_POLICY_MIN(NLA_U32, 1),
 	[NL80211_ATTR_PEER_MEASUREMENTS] =
 		NLA_POLICY_NESTED(nl80211_pmsr_attr_policy),