MAINTAINERS: ath9k-devel is closed

ath9k-devel list is now closed, only linux-wireless should be used.
Reported-by: NMichael Renzmann <mrenzmann@madwifi-project.org>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>

MAINTAINERS

@@ -10169,7 +10169,6 @@ F:	drivers/media/tuners/qt1010*
 QUALCOMM ATHEROS ATH9K WIRELESS DRIVER
 M:	QCA ath9k Development <ath9k-devel@qca.qualcomm.com>
 L:	linux-wireless@vger.kernel.org
-L:	ath9k-devel@lists.ath9k.org
 W:	http://wireless.kernel.org/en/users/Drivers/ath9k
 S:	Supported
 F:	drivers/net/wireless/ath/ath9k/