linux-firmware: add firmware for atusb driver

The atusb kernel driver is sitting in the bluetooth-next tree waiting for the
merge window to open. It's scheduled for 4.2.

Flashing goes into permanent storage and the GPLv2+ firmware allows for further
explorations. See ChangeLog for more details and links.
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
Signed-off-by: Kyle McMartin <kyle@kernel.org>

WHENCE

@@ -2772,3 +2772,13 @@ File: nvidia/tegra210/xusb.bin
 Version: v50.07
 
 Licence: Redistributable. See LICENCE.nvidia for details
+
+--------------------------------------------------------------------------
+
+Driver: atusb - ATUSB IEEE 802.15.4 transceiver driver
+
+File: atusb/atusb-0.2.dfu
+Version: 0.2
+Info: atusb/ChangeLog
+
+Licence: GPLv2+

atusb/ChangeLog

+ChangeLog:
+	* 0.0  initial release
+	* 0.1  addition of ATUSB_TEST
+	* 0.2  First public release. Compatible with atusb driver in the
+	  upcoming 4.2 kernel
+
+To flash the firmware you need dfu-util on the host:
+dfu-util -d 20b7:1540 -D atusb-0.2.dfu
+
+The firmware is flashed into permanent storage and does not need to be provided
+after power off. A new firmware version can be flashed the same way.
+
+Firmware source code is GPLv2+ and can be found here:
+http://projects.qi-hardware.com/index.php/p/ben-wpan/source/tree/master/atusb/fw