ar5523: Add firmware for new driver

AR5523 is a USB Wifi chipset that was popular circa 2005.
Better late then never.

Acked-by: Luis R. Rodriguez <mcgrof@qca.qualcomm.com>
Signed-off-by: Pontus Fuchs <pontus.fuchs@gmail.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

WHENCE

@@ -2005,3 +2005,11 @@ Source: isci/Makefile
 Licence: GPLv2
 
 --------------------------------------------------------------------------
+
+Driver: ar5523 -- Atheros AR5523 based USB Wifi dongles
+
+File: ar5523.bin
+
+Licence: Redistributable. See LICENCE.atheros_firmware for details
+
+--------------------------------------------------------------------------