staging: wlan-ng: remove unused p80211wext_handler_def declaration

p80211wext_handler_def has been removed since
commit cb3126e6 ("Staging: wlan-ng: Switch from wext
to cfg80211"), so remove it.
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Link: https://lore.kernel.org/r/20220911094255.3225461-1-cuigaosheng1@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wlan-ng/p80211netdev.h

@@ -137,8 +137,6 @@ struct p80211_frmrx {
 
 /* called by /proc/net/wireless */
 struct iw_statistics *p80211wext_get_wireless_stats(struct net_device *dev);
-/* wireless extensions' ioctls */
-extern struct iw_handler_def p80211wext_handler_def;
 
 /* WEP stuff */
 #define NUM_WEPKEYS 4