wifi: cfg80211: use IEEE80211_MAX_MESH_ID_LEN appropriately

Even if that's the same as IEEE80211_MAX_SSID_LEN, we really
should just use IEEE80211_MAX_MESH_ID_LEN for mesh, rather
than having the BUILD_BUG_ON()s.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -6223,7 +6223,7 @@ struct wireless_dev {
 			int beacon_interval;
 			struct cfg80211_chan_def preset_chandef;
 			struct cfg80211_chan_def chandef;
-			u8 id[IEEE80211_MAX_SSID_LEN];
+			u8 id[IEEE80211_MAX_MESH_ID_LEN];
 			u8 id_len, id_up_len;
 		} mesh;
 		struct {

net/wireless/nl80211.c

@@ -4205,8 +4205,6 @@ static int nl80211_set_interface(struct sk_buff *skb, struct genl_info *info)
 		if (netif_running(dev))
 			return -EBUSY;
 
-		BUILD_BUG_ON(IEEE80211_MAX_SSID_LEN !=
-			     IEEE80211_MAX_MESH_ID_LEN);
 		wdev->u.mesh.id_up_len =
 			nla_len(info->attrs[NL80211_ATTR_MESH_ID]);
 		memcpy(wdev->u.mesh.id,
@@ -4312,8 +4310,6 @@ static int _nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
 	case NL80211_IFTYPE_MESH_POINT:
 		if (!info->attrs[NL80211_ATTR_MESH_ID])
 			break;
-		BUILD_BUG_ON(IEEE80211_MAX_SSID_LEN !=
-			     IEEE80211_MAX_MESH_ID_LEN);
 		wdev->u.mesh.id_up_len =
 			nla_len(info->attrs[NL80211_ATTR_MESH_ID]);
 		memcpy(wdev->u.mesh.id,