Fix modpost failure when rx handlers are not inlined.

When CONFIG_MAC80211_MESH=n and CONFIG_MAC80211_NOINLINE=y,
gcc doesn't optimize out a call to ieee80211_rx_h_mesh_fwding,
even if the previous comparison is always false in this case.
This leads to the following errors during modpost:

ERROR: "mpp_path_lookup" [net/mac80211/mac80211.ko] undefined!
ERROR: "mpp_path_add" [net/mac80211/mac80211.ko] undefined!

Fix by removing the possibility of uninlining
ieee80211_rx_h_mesh_fwding rx handler.
Signed-off-by: NDavide Pesavento <davidepesa@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/mac80211/rx.c

@@ -1379,7 +1379,7 @@ ieee80211_rx_h_amsdu(struct ieee80211_rx_data *rx)
 	return RX_QUEUED;
 }
 
-static ieee80211_rx_result debug_noinline
+static ieee80211_rx_result
 ieee80211_rx_h_mesh_fwding(struct ieee80211_rx_data *rx)
 {
 	struct ieee80211_hdr *hdr;