wl18xx: update firmware file

- Firmware file was updated (8.9.0.0.69), includes bug fixes and improvements.
- Added Mesh support (requires supporting driver)

More information can be found here:
http://www.ti.com/tool/WILINK8-WIFI-NLCP

Signed-off-by: Yaniv Machani <yanivma@ti.com>

WHENCE

@@ -2199,7 +2199,7 @@ Version: 8.5.0.0.55
 File: ti-connectivity/wl18xx-fw-3.bin
 Version: 8.8.0.0.13
 File: ti-connectivity/wl18xx-fw-4.bin
-Version: 8.9.0.1.55
+Version: 8.9.0.0.69
 
 Licence: Redistributable. See LICENCE.ti-connectivity for details.