cfg80211: add wext handlers back to netdev for compat code

cfg80211: add wext handlers back to netdev for compat code

The patch "wext: refactor" by Johannes Berg refactored
wext code so that new kernels no longer get the wext
handlers through struct netdevice, instead they get
it through the struct wiphy which is cfg80211 specific.

For old kernels this means you get not wext handlers
anymore when backporting code, this adds the wext handler
back to the netdevice wireless_handlers to let compat
users use wext again.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>