rtlwifi: include mac80211.h from core.h

core.h references ieee80211_ops but doesn't include mac80211.h, which issues
a warning once mac80211-compat.h is taken into use.
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@adurom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rtlwifi/core.h

@@ -30,6 +30,8 @@
 #ifndef __RTL_CORE_H__
 #define __RTL_CORE_H__
 
+#include <net/mac80211.h>
+
 #define RTL_SUPPORTED_FILTERS		\
 	(FIF_PROMISC_IN_BSS | \
 	FIF_ALLMULTI | FIF_CONTROL | \