net/wireless: wireless.h: drop duplicate word in comments

Drop doubled word "threshold" in a comment.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: netdev@vger.kernel.org
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: linux-wireless@vger.kernel.org
Cc: Johannes Berg <johannes@sipsolutions.net>
Link: https://lore.kernel.org/r/20200715164325.9109-2-rdunlap@infradead.org


Signed-off-by: Johannes Berg <johannes.berg@intel.com>