mac80211: don't use kerneldoc for ieee80211_add_rx_radiotap_header

Doing so creates warnings, but the function is internal and
not part of the 802.11 docbooks, so it from kerneldoc.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index b382605..61c621e 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -103,7 +103,7 @@
 	return len;
 }
 
-/**
+/*
  * ieee80211_add_rx_radiotap_header - add radiotap header
  *
  * add a radiotap header containing all the fields which the hardware provided.