netdevice.h: check for CONFIG_WLAN instead of CONFIG_WLAN_80211

In "wireless: remove WLAN_80211 and WLAN_PRE80211 from Kconfig" I
inadvertantly missed a line in include/linux/netdevice.h.  I thereby
effectively reverted "net: Set LL_MAX_HEADER properly for wireless." by
accident. :-(  Now we should check there for CONFIG_WLAN instead.
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Reported-by: Christoph Egger <siccegge@stud.informatik.uni-erlangen.de>
Cc: stable@kernel.org

include/linux/netdevice.h

@@ -136,7 +136,7 @@ static inline bool dev_xmit_complete(int rc)
  *	used.
  */
 
-#if defined(CONFIG_WLAN_80211) || defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
+#if defined(CONFIG_WLAN) || defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
 # if defined(CONFIG_MAC80211_MESH)
 #  define LL_MAX_HEADER 128
 # else