netdev: add a channel switch event

If the connected BSS announces that it is switching operating channel,
the kernel may emit the NL80211_CMD_CH_SWTICH_NOTIFY event when the
switch is complete. Add a new netdev event NETDEV_EVENT_CHANNEL_SWITCHED
to signal to interested modules that the connected BSS has changed
channel. The event carries a pointer to the new channel's frequency.
2 files changed