cfg80211: Add wiphy_info_once()

Add wiphy_info_once() helper that prints info message only once.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210511211549.30571-1-digetx@gmail.com