ath9k_htc: add AVM FRITZ!WLAN 11N v2 support

This was reported and tested by Martin Walter over at AVM GmbH Berlin.
This also applies to 3.0.1 so sendint to stable.

Cc: s.kirste@avm.de
Cc: d.friedel@avm.de
Cc: Martin Walter <m.walter@avm.de>
Cc: Peter Grabienski <pgrabien@qca.qualcomm.com>
Cc: stable@kernel.org
Tested-by: NMartin Walter <m.walter@avm.de>
Signed-off-by: NLuis R. Rodriguez <mcgrof@qca.qualcomm.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/hif_usb.c

@@ -38,6 +38,7 @@ static struct usb_device_id ath9k_hif_usb_ids[] = {
 	{ USB_DEVICE(0x04CA, 0x4605) }, /* Liteon */
 	{ USB_DEVICE(0x040D, 0x3801) }, /* VIA */
 	{ USB_DEVICE(0x0cf3, 0xb003) }, /* Ubiquiti WifiStation Ext */
+	{ USB_DEVICE(0x057c, 0x8403) }, /* AVM FRITZ!WLAN 11N v2 USB */
 
 	{ USB_DEVICE(0x0cf3, 0x7015),
 	  .driver_info = AR9287_USB },  /* Atheros */