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.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>