cfg80211: make ieee80211_get_mesh_hdrlen() static

Fixes spares warning:
net/wireless/util.c:261:5: warning:
symbol 'ieee80211_get_mesh_hdrlen' was not declared. Should it be static?
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/wireless/util.c

@@ -258,7 +258,7 @@ unsigned int ieee80211_get_hdrlen_from_skb(const struct sk_buff *skb)
 }
 EXPORT_SYMBOL(ieee80211_get_hdrlen_from_skb);
 
-int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr)
+static int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr)
 {
 	int ae = meshhdr->flags & MESH_FLAGS_AE;
 	/* 7.1.3.5a.2 */